Four friends - A, B, C, and D - have different pets: a dog, a cat, a bird, and a fish. A does not have a dog. B has a pet that is not a bird. C has a pet that is not a fish. D has a dog. Who has the cat?
Answer: A. A
Since D has a dog, and A does not have a dog, A must have the cat. B cannot have a bird, leaving C with the bird and B with the fish.