Pro tip: A and B should be completely false in the first place.

While I, too, am of the opinion that indeed A is horribly false, B doesn't sound so-very-false to me, just a bit ill. Surely claiming that women should be paid less for the same work is a kind of negative applause light, but continue reading. The argument B is stated above as:

B: If members of one group, on average, are better at a task than members of another group, then members of that first group should be paid more than members of the second group for performing the same work.

This is certainly not something desirable, but how about this one:

B': If members of one group, on average, are better at a task than members of another group, then members of that first group should, on average, be paid more than members of the second group for performing the same work.

This transforms a bad argument into a different, not-so bad one. Now, C only states that men should, on average, be paid more for one hour of engineering. We might as well re-formulate B':

B'': Everyone should get paid for a task according to his abilities, for what he actually gets done.

This seems much better, and while I think this is more true (although not taking into account other arguments that will probably shift this position more to a more social point of view, but I don't have the time for that right here), it also avoids shooting beyond the goal by falsely coming to the conclusion that "Everyone should get paid the same for the same task!". The good: you did not do this here; The bad: I saw other people do this, especially to disprove RA's position (or whatever the argument is about). The ugly: It worked.

I'd conclude that it's often best to take a middle path, the wisdom of others is not random, and while it's not true, it's most certainly not completely false. In real life, however, I rarely see people doing this, because it's not a good way to "win" arguments.

Or did I miss something here?