Fill in the blank: If I were rich, I ____ help the poor.

The sentence "If I were rich, I ____ help the poor" is a second conditional sentence. This type of conditional is used for hypothetical or unreal situations in the present or future.

The structure for a second conditional is:
If + past simple, would + base form of the verb.

In this sentence, "If I were rich" uses the past simple ("were"). Therefore, the main clause requires "would" followed by the base form of the verb ("help").

The correct option is b).

The complete sentence is: "If I were rich, I would help the poor."

• a) will: Used for first conditional (real possibilities).
• b) would: Used for second conditional (hypothetical situations).
• c) shall: Used for future actions, often formal or for suggestions.
• d) can: Expresses ability.

The final answer is $\boxed{\text{b) would}}$.