The question asks us to identify the best explanation for why these birds choose a wooden box. The given answer choice B only explains why the birds prefer the wooden box to "highly concealing woody vegetation" but fails to account for why the wooden boxes are preferred over open grasslands. Answer C seems to more fully resolve the question. Defensive behavior from 'nest builders' ( which I have taken to mean both the birds who next in highly concealing woody vegetation and open grasslands as the wooden boxes specifically wouldn't have to be a built nest.) Taking this assumption doesn't C answer the question more fully than B.

I get the issue is probably that my assumption goes too far. But the LSAT often requires us to make leaps in logic that feel much further than the wooden box vs nest builder assumption I've made here.

Admin Note: Edited title. For LR questions, please use the format: "PT#.S#.Q# - brief description of the question."