The correct option is C in English
The part of a sentence excluding the subject is the predicate. The verb
in the predicate is often modified by an adverb or its equivalent, known
as the adverbial qualification in that predicate.
In the given sentence, "in English" is an adverbial qualification as it modifies the verb "replied" (adverbs or adverb phrases modify verbs, adjectives and other adverbs); hence option B is correct. "Rameswaram" is the subject to the verb "replied". "The teachers" is the subject to the verb "were impressed". Since these options do not modify any verb, they're not adverbial qualifications. Hence options A, C and D are incorrect.