Read this statement: 'Every square is a rectangle.' Which of the four statements below says exactly the same thing, so that it must be true whenever the given statement is true?

Turning 'if A then B' around and negating both parts gives 'if not B then not A', which always carries exactly the same meaning. Here that reads: anything that is not a rectangle cannot be a square. The traps: 'every rectangle is a square' simply swaps the two parts and is plainly false; 'anything that is not a square is not a rectangle' negates without swapping and is false too (a 4 by 7 rectangle is not a square); and 'no rectangle is a square' contradicts the original outright.