What is the default function derived from multiple inheritance in Scala?

Question

I have this piece of Scala code:

trait A {
  def message(): Unit = println("I am A")
}

trait B extends A {
  override def message(): Unit = {
    println("I am B")
  }
}

trait C extends A {
  override def message(): Unit = {
    println("I am C")
  }
}

trait D extends C {
  override def message(): Unit = {
    println("I am D")
  }
}

object Main extends App {
  (new D with A with C with B).message
  (new A with D with C with B).message
  (new A with C with D with B).message
}

The output is I am B in all three println. Could you please help me to explain why the input is the same? Thank you in advance!