Topic: Adverb (ক্রিয়াবিশেষণ),

Best Answer Explained in Below-:

The correct answer is C: "He stayed unusually long." This sentence contains the adverb "unusually," which modifies the adjective "long." Adverbs are words that modify verbs, adjectives, or other adverbs, providing additional information regarding how, when, where, and to what extent an action is performed or a quality is expressed.

In this sentence, "unusually" specifies the extent of the duration of "stayed," indicating that the length of time was beyond what is considered typical or ordinary. The other options do not contain adverbs:

- A) "I was happy to see their cheerfulness." Here, "happy" is an adjective describing the subject "I" and does not indicate action or manner.
- B) "I could hear a cacophony of loud voices." In this case, "loud" is an adjective describing "voices," while "hear" is the verb, with no adverb present.
- D) "This was the only son of Ulysses." The words here are also primarily descriptive, with "only" acting as an adjective.

Thus, option C is the sole sentence featuring an adverb that adds detail about the action of staying.