I'm sure the ATPL's grossly oversimplify this problem.
Surely a wing creates lift through the combined effects of Bernoulli's transit time principle and Newtons 3rd law. Otherwise asymetrical wings would not fly upside down, lift would not be possible at low or even negative angles of attack and you wouldn't feel backdraft from a static prop.
Therefore, the prop both pulls and pushes its way through the air.
For the ATPL exams, I agree with FFP, definately answer C, either that or the longest.