Prep Question help

Scientists have found signs that moving water changed the chemical makeup of the surface of Mars in recent eras, therefore concluding that its crust is harboring up to three times as much water than was previously thought.

(A) eras, therefore concluding that its crust is harboring up to three times as much water than was

(B) eras, therefore concluding that the planet's crust harbors up to three times as much water or more as was

(C) eras and have therefore concluded that the planet's crust harbors up to three times as much water as

(D) eras and they have concluded, therefore, that its crust harbors up to three times as much water, or more, than

(E) eras and concluded, therefore, that the planet's crust is harboring up to three times more water as was

I choose E, but the answer is C.

I think tghe "are" can't be omitted..

我说一下我的看法，关于考试点

1.比较级的表达法：as much as 是对的，as much than(A),as much or more as(B),as much or more than(D),more water as

2.therefore需要放在Concluded的前面，而不是后面，这个用OG的说法就是akward,副词直接放在它所修饰的动词的前面；

3.在表达因果关系的时候，therefore后面是不可以有逗号，而是直接跟句子的，一般不用逗号隔开；

4.关于你说的are 不可以省略，我想你是担心省略了之后的句子没有谓语动词，请你仔细看C，harbors就是谓语动词了，

希望这个能解答你的疑问。