it is a book _________ changed my life.(what was/ that has/ who had)밑줄친 부분에 들어갈 알맞은 말을 고르라는 문제인대요. who had 는 당연히안되고,what was 와 that has 무엇이 맞나요?자세한 설명도 부탁드립니다.감사합니다.