I had same opinion, but now I know why I got wrong by seeing Jonathan's explanation which is newly posted above ;)

Hi chongkwk,

I think you could have solved this question even without concretize the idea of passage.

You could select a right answer if you could have analyzed the premise-conclusion structure.

(c) is a tempting choice, but it is just referring what is said in premise part and does not precisely paraphrasing the conclusion.

I am not saying you did not have to concretize. It is certainly a great way for understanding, but I hope this way also helps your understanding because that was the way how I solved this question :D

You will find it fun by seeing your progress, Future JD27!

Due to the language barrier (I am not a native English speaker) I could not figure out what (D) exactly mean when I solve this problem, but now I can see how subtle but clear the difference between the answer and the beit. We have to be extremely careful which choice is precisely conveying the meaning of passage, as the word "unwarranted" seems adding subjective view toward the passage.

I was wondering why I got wrong with (e) will not produce a net reduction in environmental degradation, but now it is clear. We have to find the undertone which author want to deliver, that he wants to convince us electric cars may have worse environmental effect than those proponents believe. Hmm, interesting!