I find it difficult to choose between answer choice C (the credited response) and D. We're asked to resolve the paradox that the poll showed Landon would win big, but Roosevelt ended up winning big.
I understand that C highlights something that MIGHT resolve the paradox, but it could just as easily not resolve it at all. It could be the case that telephone owning voters voted for Roosevelt at the same margin as non-telephone owning voters.
D is similar to me. It's possible that poll's glaring omission of political affiliations meant nothing--that in the end, for instance, the poll actually got an equal number of Democrats and Republicans, or that the vote for Roosevelt wasn't mostly based on party lines.
But which one is more likely to be a major factor in the polls inaccuracy?! Political parties! The standard assumption would be political parties play a more important role in the way people end up voting than telephone ownership!
How can the telephone ownership issue more likely resolve the paradox?