Identify the segment in the sentence, which contains the grammatical error.
Prema is the girl in my class who write beautiful poems.

Correct option is B

Option (b) contains an error.
The error in the sentence is in segment (b), "who write". The grammatical issue here is related to subject-verb agreement.
The relative pronoun "who" refers to "the girl", which is singular. Therefore, the verb that follows should also be singular.
The correct verb form to match the singular subject "the girl" is "writes", not "write".
Grammatical rule used: The verb must agree with its subject in number and person. When the subject is singular, the verb must also be singular.
Example: She is the student who always arrives early. (Correct usage of the singular verb with a singular subject)
In this sentence, "Prema is the girl in my class who writes beautiful poems." would be the correct formation.