Question

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.

• A. Like malaria and dengue have focused either on the vaccination of humans or on exterminating
• B. Like malaria and dengue have focused either on vaccinating of humans or on the extermination of
• C. As malaria and dengue have focused on either vaccinating humans or on exterminating
• D. As malaria and dengue have focused on either vaccinating of humans or on extermination of
• E. As malaria and dengue have focused on either vaccinating humans or exterminating

Answer 1

Answer: (E)

As malaria and dengue have focused on either vaccinating humans or exterminating

The given sentence focuses on comparison. However, the sentence uses the idiom 'such...like' which is incorrect- the correct idiom used should be either 'diseases like P and Q' or 'such diseases as...'. This eliminates A and B. Then, let's focus on the placement of the preposition 'on' with regards to 'either' - the correct placement should be:

1. either on P or on Q - placement of 'on' after either requires a placement before each of the cases, here- P and Q

2. on either P or Q - if 'on' is placed before 'either' then it automatically applies to both the cases.

Here, it must be mentioned that P and Q must be parallel to each other. The second type of placement of either and on eliminates option C. Option D is eliminated on the basis of a lack of parallelism - 'vaccinating' and 'extermination' are not parallel to each other. It is only option E that rectifies the original errors without creating a bunch of its own errors. Thus, option E is our answer.