[求助]求问 一道数学题

airline

<strong><br/></strong><span id="ubbcode1">1,3/5,2/5,(&nbsp;),3/13,7/13&nbsp;<br/><br/>A.1/5,B3/10,C.5/17,D.4/15<br/><br/>会的说一下理由&nbsp;&nbsp;十分感谢<br/></span>