Can someone explain this weird sentence structure?

<p>(An odd friendship) in certain respects, she being an outdoor enthusiast and he a dedicated bookworm.</p>

<p>A. An odd friendship
B. As an odd friendship
C. Their friendship being odd
(D.) Theirs was an odd friendship
E. Having a friendship that was somewhat odd</p>

<p>D is correct, but I don't know why. Can someone explain what rule is broken here and why each of the other answers is wrong? I chose A and kept the sentence the same; why does that not work?</p>

<p>D</p>

<p>It doesn’t have an object. WHAT was an odd friendship? THEIRS was an odd friendship.</p>

<p>Not sure if I explained it properly, but that is the problem with the sentence and only D satisfies it. The rest aren’t complete sentences.</p>

<p>Okay I think I see it now, thanks!</p>

<p>This is a sentence fragment issue I think. The first part of the sentence should be an independent clause.
If u look closely, only D makes an independent clause. Though I am not really sure.</p>