This is becomes a self-referential paradox. Both A and D would be correct if there were four unique answers, but since A and D are the same answer, the chance that you would choose a correct answer is 50%, which makes B correct. But if there’s only one correct answer, the odds of choosing the correct one at random goes back to 25%. And around and round you go.

There’s a lot of discussion at Richard Wiseman’s blog and more at Lifehacker, where I first saw this.

Eat (8) flush (plus) to (2) my nose (minus) tree (3) times (times) for (4) they buy dead by (divided by) too (2).

There are two answers depending on whether you calculate as you read or calculate the entire solution at the end.
8 + 2 = 10, – 3 = 7, x 4 = 28, / 2 = 14
or
8 + 2 – 3 x 4 / 2 = 10 – 6 = 4

R. It’s a representation of a stick shift, where 1-5 are gears and R represents reverse.