I have three stuffed animals: an ant, a bat, and a cat. One is red, one is white, and one is blue. Exactly one of these statements is true:
Tell the color of each animal.
We have to solve this problem in two steps. First, we have to figure out which one statement is true. If (a) is true, then (b) is also true, so (a) is not the one true statement. If (b) is true, then either the ant or the cat is red, so either (a) or (c) is also true. Thus (b) is not the one true statement. Therefore, (c) is the only statement that can be true while the other two are false.
Since (b) is false, the bat is red, so the cat must be white (not blue or red), and the ant is blue.