as soon as she entered the room,the girl caught sight of the

as soon as she entered the room,the girl caught sight of the flowers______by her mother
A)buying
B)being bought
C)which were bought
D)bought
请说明选择的原因,flowers是复数,为什么后面省略的是which was 而不是which were
2)the result of this experiment is better than______of the last one
A)that
B)which
C)it
D)what
请说明选择的原因,为什么不能选其他答案,并翻译全句