Before reading ahead, you must know the fact that only one of the person here is telling the truth.

A says that B is lying.
B says that C is lying.
C says both A and B are lying.

Can you find out who is speaking the truth?

Who Is Speaking The Truth Puzzle

B is speaking the truth.

A is lying when he says that B is lying. B is telling the truth when he says that C is lying. C is lying when he says that both A and B are lying since one of them is speaking the truth.