XSLT choose first match

I have a xml with the strucure:

<a>
  <b>
    <c>abc</c>
  </b>
  <b>
    <c>efg</c>
  </b>
  <b>
    <c>efg</c>
    <d>1-123456789</d>
    <d>2-123456789</d>
  </b>
  <b>
    <d>1-123400000</d>
    <d>2-123400000</d>
    <d>3-123400000</d>
  </b>
</a>

How do I select the first occurance of d? a/b/c/d[1] ?