Pumas, which are large, cat-like animals, will not attack human beings if they ________ undisturbed.
句意：大型猫科动物美洲狮，如果未受干扰是不会袭击人类的。leave sb./sth.+形容词/过去分词意为“使某人/某物处于某种状态”，所以这里应该用被动，答案选C。