Blood banks can only make a donation useful to a hospital by testing them quickly for a variety of illnesses and, before they expire, distributing them.



(A) by testing them quickly for a variety of illnesses and, before they expire, distributing them


(B) by testing it quickly for a variety of illness and distributing it before expiration


(C) by quickly testing it for a variety of illnesses and distributing it before it expires


(D) by quickly testing it for a variety of illnesses and by, before they expire, distributing them


(E) by quickly testing it for a variety of illnesses and to distribute it before it expires


This question is based on Pronouns and Parallelism.


Option A contains two ambiguous pronouns – them and they. These pronouns do not have a logical antecedent because plural pronouns cannot refer to the singular antecedent ‘a donation’. So, Option A can be eliminated.


Option B corrects the pronoun reference error committed in Option A. However, the adverb ‘quickly’ is misplaced. It should modify the participle ‘testing’ and so should be placed before it to avoid confusion. Furthermore, the phrase ‘before expiration’ is awkward and lacks clarity. So, Option B can be eliminated. 


Option D is wordy. The phrase “by, before they expire’ is nonsensical. The preposition ‘by’ can precede a noun to convey a time by which an action should take place but it cannot precede a clause to convey the same meaning. So, Option D can be eliminated. 


The sentence states that blood banks can make a donation useful by doing two things – testing and distributing. So, these two actions must be parallel in form. Option E lacks this parallelism, so it can be eliminated.


Option C maintains parallelism. This option also contains the appropriate pronoun reference. The singular pronoun ‘it’ can be used to refer to the singular antecedent ‘a donation’. Therefore, C is the most appropriate option.