Most efforts to combat such mosquito-borne diseases like malaria and dengue have focused either on the vaccination of humans or on exterminating mosquitoes with pesticides.
(This question is from Official Guide. Therefore, because of copyrights, the complete question cannot be copied here. The question can be accessed at GMAT Club)
The sentence essentially means that most efforts to combat diseases have focused on either of the two things:
- vaccination of humans
- exterminating mosquitoes with pesticides
The first problem with the sentence is that it uses “like” with “such”. Even though “like” can be used to offer examples (OG17 Q685 uses like to offer examples), it cannot be used in conjunction with “such”. You either use “such as” or “like”; don’t mix them together. It’s incorrect.
Also, since we are using action noun “vaccination” in one part of the “either or” structure, it is highly preferable to use action noun instead of the currently used gerund “exterminating”. Or we can have both in the form of gerunds.
Therefore, the original sentence has one major error and one area of improvement.
(A) Incorrect. For the errors mentioned above.
(B) Incorrect. Incorrect. For the following reasons:
- “Such like” is idiomatically incorrect.
- “Vaccinating” is not entirely parallel to “the extermination”. When we have an action noun for a verb, it is always recommended to use the action noun to make it parallel to an action noun or another noun. Therefore, it is highly preferable to use “vaccination” instead of “vaccinating”. In addition, “vaccinating of humans” should be preceded by “the”. Please note that we should never use an article in front of the construction “vaccinating humans” (i.e. simple gerund). However, in constructions such as “vaccinating of humans” (complex gerunds), we generally have an article.
(C) Incorrect. The part after “either” – vaccinating – and the part after “or” – on exterminating – are not parallel. One is a gerund; the other is a prepositional phrase. In addition, they are not even logically parallel. One cannot replace the list with the second element of the list.
(D) Incorrect. The part after “either” – vaccinating – and the part after “or” – on extermination – are not parallel. One is a gerund; the other is a prepositional phrase. In addition, they are not even logically parallel. One cannot replace the list with the second element of the list.
(E) Correct. This option uses the correct idiom “such as”. Also, “vaccinating” and “exterminating” are parallel.