1. people in some societies you may marry more than one time.

(a) have been different about
(b) have differed as to whether
(c) have differed concerning what
(d) have been different with regard if

ㅡ 답은 b인데요 맞긴 맞았습니다. 근데... d는 답이 안되나요? 딱히 안될건없어보이는데;; 자세히 설명해주세요!

2. the stardust space mission grabbed comet dust almost two years ago and its precious cargo on january 15.

(a) will return with
(b) return
(c) will return
(d) will returning

ㅡ 답은 c인데요 a는 안되나요? 그 우주선이 귀중한 화물(cargo)와 함께 돌아올것이다. 이렇게 하면안되나요?
궁금하네요...

3. a rent is money paid for the use of a capital asset, whether land, a building, an office, a car, a bicycle, or which someone might want but cannot or does not want to own.

ㅡ 밑줄친 부분이 틀렸다는데요.. 어떻게 고쳐주면 좋을까요? 그리고 정확히 왜틀렸는지도 궁금합니다.

4. people who get a high score on the hope scale have had many hard times asthose with low scores, but have learned to
think about it in a hopeful way.

ㅡ 여기서 밑줄 친 as는 as의 어떤용법인가요? 어떤 품사로 쓰인건지;; 그리고 여기서 as의 뜻도 궁금해요!아시는분은 답변 부탁드립니다~