The following sentence has been split into four segments. Identify the segment that contains a grammatical error.
My sister Mona / never drinks coffee; / she prefer tea / in the morning.

The segment containing an error is "she prefer tea".
Correct sentence: She prefers tea in the morning.
Explanation:
· "She" is a singular subject, so the verb must be in the third-person singular form.
· The correct form of the verb "prefer" in the present simple tense for "she" is "prefers" (not "prefer").
Grammatical rule used:
· In the present simple tense, singular subjects (he, she, it) take verbs with "-s" or "-es" (e.g., she prefers, he eats).
Example:
· Incorrect: He like coffee.
· Correct: He likes coffee.
Meanings of other segments:
· "My sister Mona" (correct, subject of the sentence).
· "never drinks coffee;" (correct, verb in the correct form).
· "in the morning." (correct, adverbial phrase).