I got a perfect score the first time, of which I am very proud, since I didn't really know how to go about #2 and #5, but reasoned for #8 that since the question was there, it had to have an answer, so there must be an obvious pattern in the other answers. Looking at a?cd?bc? I conjectured it was abcdabcd, et voila, it worked. This answer key corresponds to my reasoning on the questions I got right (#1, pick the answer that reuses the word, #4 and #7 "answer each other" but I didn't pick up on the fact that #4's "an" tells you the answer has to start with a vowel, #3 pick the one that is making the weaker quantifier-claim, #6 since the question has a universal quantifier, pick the smallest set) For #2 I wanted to choose (a) since it reused a word from the question, but (b) did seem compelling since it was a long, specific answer that had the smell of "well actually" pedantic truth about it. #5 I didn't pick up on the grammatical number agreement and let my answer for #8 force my hand instead.
An alternate jokey explanation for #8: since, after some thought, the first three answers are revealed to be essentially the same, the answer must be "all of the above" or "none of the above", which is always (d).
Holy dang this joke is OLD. Here's people talking about it 1981:
Is that that Mary Shaw, I wonder?