I've found a few examples and some contradictory things about the .row class in bootstrap. Is it better to do
a)
<div class="container">
<div class="row">
<div class="col-md-12">
</div><!-- .col-md-12 -->
</div><!-- .row -->
<div class="row">
<div class="col-md-6">
</div><!-- .col-md-6 -->
<div class="col-md-6">
</div><!-- .col-md-6 -->
</div><!-- .row -->
</div><!-- .container -->
or
b)
<div class="container">
<div class="row">
<div class="col-md-12">
</div><!-- .col-md-12 -->
<div class="col-md-6">
</div><!-- .col-md-6 -->
<div class="col-md-6">
</div><!-- .col-md-6 -->
</div><!-- .row -->
</div><!-- .container -->
Or does it not matter?