Topic: Pronoun (সর্বনাম),

Best Answer Explained in Below-:

The sentence "I know the man __ has a wooden leg." requires a relative pronoun that correctly connects the main clause to the specific noun, "the man." In this context, the options provided include "who," "which," "that," and "what."

The correct answer is "who" (Option A) because it refers specifically to people. In English, "who" is the appropriate choice when the antecedent (the noun it relates to) is a person or people. Here, "the man" refers to an individual, making "who" the suitable pronoun.

Option B, "which," is typically used for animals or objects, not for human subjects. Option C, "that," can sometimes refer to people, but it is more commonly used for objects or clauses that provide essential information. However, "who" is more precise and standard in identifying individuals. Finally, Option D, "what," does not fit the structure of the sentence since it typically introduces a noun clause rather than serving as a relative pronoun.

Thus, "who" is the most fitting and grammatically correct choice to convey the intended meaning clearly and accurately.