The poll lacks an option for those people who have already read the article and want to see the results.

Haha. The second I read the first sentence of that bit in the article I knew my mistake.

This question was included on the 2012 LW Census/Survey.

You may want to take a guess at the results from that survey (perhaps after reading the SciAm article, but before following my link to the survey results). What percent of LWers who took the 2012 census/survey answered the question correctly? And, what percent answered it correctly among the subset of LWers who said that they had read "Nearly all of the Sequences"?

Answers: gur erfhyg jnf gung sbegl fvk creprag bs yrff jebatref tbg vg pbeerpg, vapyhqvat svsgl rvtug creprag bs gubfr jub'q ernq gur frdhraprf.

The only two things that even slowed me down were, first, "This is supposed to be hard? Where's the catch?", and second, "Are they pointed the wrong way?"

Damn, I got it wrong.

Semi-spoiler below.

It did not occur to me to "check all cases". Had this been a math problem about the parity of numbers or some such, I would immediately think "well, A can be either even or odd. If A is odd, then ...; and if A is even then ...; QED".

However, my conscious thought process went more like "We can't tell whether Anne is married, since Jack does not have to be married to her if more than three people exist. We don't know who George is looking at, so the answer must be C."

For this problem you can also get the right answer by reasoning wrongly: "Jack must be married to Anne, so the answer is A."

Dammit, I got it wrong. :(