(b) B: I've only ever been hiking once, but I would like to do it again.
(c) A: Really? What did you enjoy the most about the experience?
(d) B: When I reached the summit, I had the most spectacular view of surrounding landscape.
what do you think among those above from (a) to (d) is wrong grammatically?
친구가 질문한건데...설명을 못하겠네요...ㅠㅠ 도와주세요...