(A) Incorrect. For the error mentioned above.

(B) Incorrect. Same error as in the original sentence.

(C) Incorrect. Same error as in the original sentence. Also, the structure “X is likely that X will do” is incorrect. The correct structure is “X is likely to do…”.

(D) Incorrect. The structure “X is likely that X will do” is incorrect. The correct structure is “X is likely to do…”.

(E) Correct. This option uses the correct idiom “as…as”. Many people find this option incorrect because of the structure at the end “they are the current one”. This structure uses ellipsis; the words “likely to exceed” are elided. Without the ellipsis, the structure will read “as they are likely to exceed the current one”. Now, it makes perfect sense. Right?

So, you have to see if the structure uses ellipsis, and then see if the structure will make sense by inserting a few words from the previous part of the comparison.

Also, it’s important to understand that in the original sentence, even the subject and verb were elided after “as” (The original sentence has “as the current one”). However, given that the verbs (“will be” and “are”) are different in the two parts of the comparison, it is strongly preferable to mention the verb in the second part instead of eliding it.