(A) are usually able to be modified to make them a more effective drug.
(B) are usually able to be modified to make them more effective drugs
(C) are usually able to be modified, which makes them more effective drugs
(D) can usually be modified to make them a more effective drug
(E) can usually be modified to make them more effective drugs
Solution:
Idioms + Pronoun
are usually able to be is passive and sounds awkward and therefore can usually be should be preferred. Hence, A, B, and C are incorrect. Moreover, in A, drug should be in plural form because antibiotics is plural- antibiotics to make them a more effective drug(s)
In D, them refers to antibiotics which is plural. Therefore, drug should also be plural in form. antibiotics can .to make them a more effective drug. Hence, D is incorrect.
In E, drugs is correctly used in the plural form and hence, E is the best choice.
Sentence Correction - 1000 Questions with Solution: