Which of the following phrases given below the sentence should replace the phrase printed in bold letters to make the sentence grammatically correct? Choose the best option among the five given alternatives that reflect the correct use of phrase in the context of the grammatically correct sentence. If the sentence is correct as it is, mark “No improvement required” as the answer.

Since the prisoner couldn’t coexist by another convicts, he spent a lot of time in solitary confinement.

Correct option is C

The correct answer is (C).

Error Analysis

The original phrase "coexist by another convicts" contains two distinct errors:

1. Prepositional Error: The verb "coexist" requires the preposition "with" when describing living or existing together with others. "By" is incorrect in this context.
2. Number Agreement: The word "another" must be followed by a singular noun (e.g., another convict). Since the sentence uses the plural "convicts," the adjective should be "other."

Why the other options are incorrect:

• A: Uses "coexists" (singular verb form), which doesn't work with the auxiliary verb "couldn't." After a modal verb like can, could, should, or would, you must use the base form of the verb (coexist). It also incorrectly mixes "other" with the singular "convict."
• B: Uses "coexisted," but after the modal "couldn't," we need the base form, not the past tense. While "among" is a possible preposition, "with" is the more standard idiomatic pairing for "coexist."
• D: Uses "within," which implies being inside the bodies of the other convicts, and changes the pronoun "he" to "it," which is illogical for a prisoner.

Grammar Rule: Modal Verbs and Prepositions

When using modal auxiliary verbs (like could), the following verb must be in its base form (the infinitive without "to"). Additionally, verbs often have "fixed prepositions" that must be used to make sense.

• Rule: Modal (couldn't) + Base Verb (coexist)
• Collocation: Coexist + with
• Adjective Agreement: Another + Singular / Other + Plural

Example

• Incorrect: I cannot coexists by the noise.
• Correct: I cannot coexist with the noise.
• Correct: He prefers to work with other people rather than another person.