Which statement is logically equivalent to "If Yoda cannot use a lightsaber, then he cannot help Luke win the battle."

Question

(A) Yoda cannot use a lightsaber and he will help Luke win the battle. (B) If Yoda can help Luke win the battle, then he can use a lightsaber. (C) Yoda can use a lightsaber if and only if he can help Luke win the battle. (D) Yoda cannot use a lightsaber and will not help Luke win the battle.