Self-referential aptitude test

The *self-referential aptitude test* (SRAT) is a list of 20 multiple-choice questions, many of which are referring to each other. It was designed by James Propp, a professor of mathematics at the University of Massachusetts Lowellt.

Among them is this question, for example:

```
19. The answer to this question is:
(A) A
(B) B
(C) C
(D) D
(E) E
```

Even though, the test has a unique solution (and in fact, this knowledge is really helpful for finding the answer to some questions).

- Homepage, containing the original questions, a interactive version, and many detailed approaches to find the solution.