Fact 1: Mary said, "Ann and I both have cats."<br>Fact 2: Ann said, "I don't have a cat."<br>Fact 3: Mary always tells the truth, but Ann sometimes lies.<br><br>If the first three statements are facts, which of the following statements must also be a fact?<br>I: Ann has a cat.<br>II: Mary has a cat.<br>III: Ann is lying.<br>

Correct Answer: All the statements are facts.
If Mary always tells the truth, then both Ann and Mary have cats (statements I and II), and Ann is lying (statement III). So all the statements are facts.