Select the most appropriate option to substitute the highlighted segment in the given sentence. If there is no need to substitute it, select ‘No improvement’.
Sentence: Undercover officers were sent to gather information, and they gave evidence in court from behind screens to protect their identities.

Correct option is C

The correct substitution is (c) No improvement.
Explanation:
The phrase “to protect their identities” is grammatically and contextually correct.
“To + base verb” is the correct infinitive form used to express purpose.
Grammatical rule used:
Infinitive of purpose: When stating the reason or purpose of an action, use "to + verb"
Example: She left early to avoid traffic.
Incorrect options:
· (a) for protecting his identities – “his” is incorrect; also “identities” should be singular for one person.
· (b) in protecting their identity – "in protecting" is incorrect use of preposition; also singular/plural mismatch.
· (d) to protecting – incorrect form; “to” must be followed by base verb, not gerund.