“আমি যদি আগেই জানতাম!”

• Correct Answer: খ) If I had known earlier!

- “আমি যদি আগেই জানতাম!”
Structure: If + past perfect → main clause (optional with would/could/should + have + past participle).
- It correctly reflects an unreal condition in the past - something that did not happen.

• Incorrect Options:
ক) If I would know earlier!
- Grammatically incorrect. In conditional sentences, “would” is not used in the if-clause.

গ) If I knew earlier!
- This is a present unreal structure. But the Bengali sentence expresses past regret, so it's incorrect.

ঘ) I should know it earlier!
- “Should know” implies present obligation or mild advice, not past regret. Also, the verb tense is incorrect for expressing something that didn’t happen in the past.

Source: Merriam-Webster Dictionary, Accessible Dictionary, Cambridge Dictionary.