Topic: Pronoun (সর্বনাম),

Best Answer Explained in Below-:

In the sentence "Each of the sons followed - father's trade," the word "each" is a singular pronoun that refers to individual members of a group. When we use "each," it emphasizes the individuality of the sons, despite their collective nature. Therefore, any pronoun that follows should also be in the singular form.

When considering the options:

A) "their" is a plural possessive pronoun, which does not agree with the singular subject "each."
B) "her" refers to a female, which is incorrect since we are discussing sons and their father.
C) "whose" is a relative pronoun; while it could technically fit, it does not directly indicate possession in the context of the father’s trade as effectively as a possessive pronoun would.
D) "his" is a singular possessive pronoun that refers directly to "father," aligning perfectly with the singular nature of "each."

Therefore, the correct option is D) "his," as it accurately maintains grammatical consistency and conveys that each son is following the trade of their individual father.