Confound is one of the trickier and more subtle words in GRE vocabulary. Usually it is used to mean either to make completely confused (as in, the calculus problem confounded him), or to be confused (he was confounded and hastily closed the calculus book.)
Complicating—or confounding, if you will—things a little is the fact that confounding can specifically refer to confusing something because you mixed it up (not because it was some arcane math theorem.) For instance, those with red-green color blindness have trouble telling the two colors apart. Therefore, they tend to confound (or be confounded by) the average Christmas tree.
Now if that weren’t confounding enough, confound also has several other definitions that do not relate to confusion. To confound someone is to damn or curse them (maybe you’re thinking, I confound the GRE!) To confound can also mean to refute, as in very few of Einstein’s theories have been confounded.
But it doesn’t end there. Two more esoteric definitions include to embarrass/abash and to waste, the latter being obsolete (though probably not to the folks who write the GRE.)
So with that said, try the following problem.
The answer? Not (E). Yep, it’s a trick antonym. A through D could all work. Sorry for confounding you, but please don’t confound me!