Answer choice B got me ecause I saw the jump from "effective" to "extremely effective", so thought the flaw would be around that jump.

One, B is wrong because it says "as if it had been repeated 1,000 times", so the directions weren't actually repeated more than once.

Two, B is wrong because it says the advertisement takes for granted that "the subconscious is always directly proportional..." which goes beyond what the advertisement said. Assuming that the instructions were actually repeated 1,000 times, I think this answer choice would be a lot mroe appealing if it said "is directly proportional" instead of "always directly proportional"

LSAT 154, section 2, question 22 is a great example of where this is important