Select the option that will improve the highlighted part of the given sentence. In case no improvement is needed, select 'No improvement required'.
When a plastic comb is rubbed on dry hair, they acquired a static charge.

Correct option is B

The correct substitution of the highlighted words is (b) "it acquires a".
Explanation:
· "A plastic comb" is singular, so the pronoun referring to it must be singular, i.e., "it" instead of "they."
· The sentence is describing a general scientific fact, so we use present simple tense: "acquires" instead of "acquired."
· "A static charge" is correct as "static charge" is countable in this context.
Grammatical rule used:
· Singular noun takes a singular pronoun.
· General facts are stated in simple present tense.
Example:
Incorrect: When a balloon is rubbed, they gain an electric charge.
Correct: When a balloon is rubbed, it gains an electric charge.