edit this select template in order to Add style to a specific word inside option in a drop-down jquery styled select

Question

I'm modifying select template, and on one of the option which is 3 Month 30$ 25$ I want to add line through in the 30$ so user can see that for 3 months subscription there is a discount of 5$.

I've tried finding information or examples, but as I'am new in jquery I had difficulties.

Here is HTML:

  <div class="center">
    <select name="sources" id="sources" class="custom-select sources" placeholder="chose">
      <option value="onemonth">1 Month 10$</option>
      <option value="twomonth">2 Month 20$</option>
      <option value="threemonth">3 Month 30$ 25$</option>
    </select>
  </div>

Here is CSS:

body {
  background: #ededed;
  font-family: 'Open Sans', sans-serif;
}
.center {
  position: absolute;
  display: inline-block;
  top: 50%; left: 50%;
  transform: translate(-50%, -50%);
}

/**#ic, #passport, #exampleId, #test { display: none; }**/
.custom-content { display: none}

/** Custom Select **/
.custom-select-wrapper {
  position: relative;
  display: inline-block;
  user-select: none;
}
  .custom-select-wrapper select {
    display: none;
  }
  .custom-select {
    position: relative;
    display: inline-block;
  }
    .custom-select-trigger {
      position: relative;
      display: block;
      width: 230px;
      padding: 0 84px 0 22px;
      font-size: 22px;
      font-weight: 300;
      color: #fff;
      line-height: 60px;
      background: #5c9cd8;
      border-radius: 4px;
      cursor: pointer;
      text-align: center;
    }
      .custom-select-trigger:after {
        position: absolute;
        display: block;
        content: '';
        width: 10px; height: 10px;
        top: 50%; right: 25px;
        margin-top: -3px;
        border-bottom: 1px solid #fff;
        border-right: 1px solid #fff;
        transform: rotate(45deg) translateY(-50%);
        transition: all .4s ease-in-out;
        transform-origin: 50% 0;
      }
      .custom-select.opened .custom-select-trigger:after {
        margin-top: 3px;
        transform: rotate(-135deg) translateY(-50%);
      }
  .custom-options {
    position: absolute;
    display: block;
    top: 100%; left: 0; right: 0;
    min-width: 100%;
    margin: 15px 0;
    border: 1px solid #b5b5b5;
    border-radius: 4px;
    box-sizing: border-box;
    box-shadow: 0 2px 1px rgba(0,0,0,.07);
    background: #fff;
    transition: all .4s ease-in-out;
    text-align: center;

    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transform: translateY(-15px);
  }

  .custom-options .under{
    text-decoration: underline;
  }


  .custom-select.opened .custom-options {
    opacity: 1;
    visibility: visible;
    pointer-events: all;
    transform: translateY(0);
  }
    .custom-options:before {
      position: absolute;
      display: block;
      content: '';
      bottom: 100%; right: 25px;
      width: 7px; height: 7px;
      margin-bottom: -4px;
      border-top: 1px solid #b5b5b5;
      border-left: 1px solid #b5b5b5;
      background: #fff;
      transform: rotate(45deg);
      transition: all .4s ease-in-out;
    }
    .option-hover:before {
      background: #f9f9f9;
    }
    .custom-option {
      position: relative;
      display: block;
      padding: 0 22px;
      border-bottom: 1px solid #b5b5b5;
      font-size: 18px;
      font-weight: 600;
      color: #b5b5b5;
      line-height: 47px;
      cursor: pointer;
      transition: all .4s ease-in-out;
    }
    .custom-option:first-of-type {
      border-radius: 4px 4px 0 0;
    }
    .custom-option:last-of-type {
      border-bottom: 0;
      border-radius: 0 0 4px 4px;
    }
    .custom-option:hover,
    .custom-option.selection {
      background: #f9f9f9;
    }

and jquery is:

$(".custom-select").each(function() {
  var classes = $(this).attr("class"),
      id      = $(this).attr("id"),
      name    = $(this).attr("name");
  var template =  '<div class="' + classes + '">';
      template += '<span class="custom-select-trigger">' + $(this).attr("placeholder") + '</span>';
      template += '<div class="custom-options">';
      $(this).find("option").each(function() {
        template += '<span class="custom-option ' + $(this).attr("class") + '" data-value="' + $(this).attr("value") + '">' + $(this).html() + '</span>';
      });
  template += '</div></div>';
  $(this).wrap('<div class="custom-select-wrapper"></div>');
  $(this).hide();
  $(this).after(template);

});

$(".custom-option:first-of-type").hover(function() {
  $(this).parents(".custom-options").addClass("option-hover");
}, function() {
  $(this).parents(".custom-options").removeClass("option-hover");
});

$(".custom-select-trigger").on("click", function() {
  $('html').one('click',function() {
    $(".custom-select").removeClass("opened");
  });
  $(this).parents(".custom-select").toggleClass("opened");
  event.stopPropagation();
});

$(".custom-option").on("click", function() {
  $(this).parents(".custom-select-wrapper").find("select").val($(this).data("value"));
  $(this).parents(".custom-options").find(".custom-option").removeClass("selection");
  $(this).addClass("selection");
  $(this).parents(".custom-select").removeClass("opened");
  $(this).parents(".custom-select").find(".custom-select-trigger").text($(this).text());

});

I expect the line through to be shown not only at the 3rd options but also in the placeholder after choosing it. thank you guys.