I believe you have a typo when it comes to the first option - it should be athletics, not athletic. The word athletic is an adjective, and the word athletics is a noun.
That being said, the correct answer is A. athletics. Even though this noun ends in -s, it is still singular. The rest of the options are all plural nouns.
Answer:
<em>Combining</em><em>:</em>
<em>He</em><em> </em><em>is</em><em> </em><em>nor</em><em> </em><em>Intell</em><em>igent</em><em> </em><em>nor</em><em> </em><em>dilige</em><em>nt</em><em>.</em><em>.</em><em>.</em><em>.</em>