In a magical swamp there are two species of talking amphibians: toads, whose statements are always true, and frogs, whose statements are always false. Four amphibians, Alice, Bob, Carol, and David live together in this swamp, and they make the following statements.
Alice: "Bob and I are the same species."
Bob: "Carol is a frog."
Carol: "David is a toad."
David: "Exactly three of us are frogs."
How many of these amphibians are frogs?
0
1
2
3
4
