为什么不选C呢？cost，get和allow平行，allow passengers to have a …ride. have a ride的主语难道不该是人吗?

为什么不选C? Minivans 是这个动词的主语， Minivans carry...get...and allow..最后那个 and have a smoother ride的主语应该是passengers..

要看清楚列举不一定只有三者，也可以是三者以上，所以需要注意未划线部分已经有一个and了，所以前面不应该再加and

Typically, the structure "make it easy" or "make it easier" is followed by an infinitive, perhaps an infinitive with the subject of the infinitive in a "for" prepositional phrase.
. . . make it easy for passengers to get in and out . . .
Choice (A) would be correct if it didn't have the "and" at the beginning messing up the parallelism.

What's subtle and funny about (D) is that it almost feels as if there's a missing infinitive . . .
. . . make it easier for passengers to do something? when getting in and out . . .
Because the infinitive is so often used, and so often follows a "for" preposition, having something else makes the sentence feel as if an infinitive should be there somehow.

Also, the construction of (D) is technically illogical--it's a colloquial construction that native speakers use frequently in informal conversation, but it doesn't withstand logical analysis. Here's the correct construction again:
. . . make it easy for passengers to get in and out . . .
What is made easier? The act of getting in and out. The "dummy it" refers to the infinitive. That make sense.
Now, (D).
. . . make it easier for passengers when getting in and out . . .
What is made easier? The "dummy it" appears to refer to the subordinate clause beginning with "when." The "when" clause denotes a time. How is time itself "made easier?" Yes, yes, colloquial, people say stuff of this sort all the time ("she made lunchtime easier," "our end-of-year shopping package makes your holidays easier") It's colloquial and technically illogical. What is meant is that we something easier for someone at that time--we didn't make it easier for the time itself.

All of those are problems with (D).

remember that parallelism is really of 2 types: GRAMMATICAL and LOGICAL.

in your case, v1 though v5 all happen to be in the same tense - present tense, because we're talking about unchanging features of minivans - but ONLY v2 through v5 are LOGICALLY parallel.
v1 describes the van's passenger seating capacity, which is NOT presented as a point of superiority over sport utility vehicles, while v2 through v5 specifically describe advantages of minivans over sport utility vehicles.
therefore, the sentence is written with v2 through v5 in list form, but, because v1 isn't in the same category as those others, it's (rightfully) excluded from that list.

when后面省略的主语应该是主句的主语

参考其他人的解释：
整个句子结构是：
[Minivans(主语) carry... ] and [ most(主语) cost..., get..., allow... and have...]
结构就是两个分句的大平行。
后面分句的主语是most指代Minivans
这题真的很tricky！

D选项when省略的主语应该是主句主语

D. it指代不清，make it easier for passengers结构不如E简洁。

D不对 when从句主语是主句主语

此题是 A，B，C，and D 结构？