Topic: Conditional Sentence,

Best Answer Explained in Below-:

The phrase "Had I been a king," is a conditional statement that sets up a scenario in the past which did not actually occur. In English, when forming a hypothetical situation in the past, the correct structure typically uses "would have" to indicate what would result from that hypothetical condition.

Option B: "would have helped the poor" is grammatically correct because it correctly follows the third conditional structure, which is used to express unreal situations in the past. It conveys that if the speaker had been a king (which they were not), they would have taken action (helped the poor).

In contrast, the other options fail to adhere to the standard English grammar rules for conditional sentences. Option A "had helped the poor" misuses the form, as it suggests an action that was completed, rather than a potential action based on a past hypothetical. Option C "have helped the poor" does not fit the conditional construction at all, and D "helped the poor" similarly lacks the necessary auxiliary verb "would" to convey the conditional meaning.

Thus, "would have helped the poor" accurately represents the intended hypothetical scenario, making it the correct choice.