Topic: verb (ক্রিয়া),

Best Answer Explained in Below-:

The essential part of a sentence is the verb, as it is the word that expresses action, occurrence, or a state of being. A verb is fundamental to conveying the main thought or idea of a sentence, functioning as the backbone that reflects what the subject of the sentence is doing or experiencing. Without a verb, a sentence lacks crucial information needed to convey a complete thought, making it incomprehensible.

For example, in the sentence "The dog barks," the verb "barks" tells us what the subject, "the dog," is doing. This structure allows listeners or readers to understand the action being performed. In contrast, while nouns are important for identifying subjects or objects within a sentence, they cannot fully express an idea without a verb. Other options, such as "hard words" and "felling," do not carry the same grammatical necessity or function in constructing meaningful sentences.

In summary, understanding that verbs communicate essential actions and states of existence is key to grasping the structure of sentences and the English language as a whole, which is why "B: Verb" is the correct answer.