Question

Two valence states of uranium, one with a deficit of four electrons and the other one with a deficit of six occurs in nature and contributes to the diversity of uranium’s behaviour.

• A. the other with a deficit of six, occurs in nature and contributes
• B. one with six occurs in nature and contributes
• C. the other one a deficit of six, occur in nature and contribute
• D. the other with a deficit of six, occur in nature and contribute

Hint:

In complex sentences with parallel descriptions, ensure both grammatical parallelism and correct subject–verb agreement.

Answer 1

The Correct Option is A

The sentence describes two valence states of uranium, so grammatical agreement between subject and verb is essential.
The subject here is singular in structure — “Two valence states of uranium” as a compound subject is treated as a single concept, hence the singular verb “occurs” is correct.
Option (a) correctly uses “the other with a deficit of six” as a parallel structure to “one with a deficit of four electrons,” maintaining symmetry and clarity. It also keeps the verb singular (“occurs”) and matches it with “contributes” later.
Option (b) incorrectly changes the meaning by stating “one with six,” which contradicts the earlier statement about a deficit of four for the first state and a deficit of six for the second.
Option (c) omits “with” before “a deficit of six” and uses “occur” and “contribute,” which incorrectly make the verb plural, breaking agreement.
Option (d) maintains “with a deficit of six” but uses plural verbs “occur” and “contribute,” which is grammatically inconsistent with the intended singular subject.
Therefore, option (a) is the most accurate, grammatically correct, and parallel version of the sentence.