OA is D. Celebrate guys all of us are correct
and our cumulative explanation on the problem has done justice to the kind of quality question it is. @iwg770
You are valid that choice of "x of y" over "y's x" is not a rule of thumb. It depends on the context, as you have mentioned. Apart from subject emphasis, parallelism is one more factor to decide. In a list or comparison, keep all in same form - "x of y" or "y's x". Still, given a choice between "x of y" and "y's x", while everything else is same, then I would prefer "x of Y."
@Vivek and ronniecoleman
Your point on contradiction is perfect.
