Explanation:

- A bill of exchange is a written order to pay a certain sum to a specified person.

- Acceptance means the drawee signs the bill, agreeing to pay.

- Option 1: Compulsory – Correct Answer. Acceptance is compulsory for a bill of exchange to be valid unless it is a bearer bill or payable on demand.

- Option 2: Optional – Not correct, because normally, acceptance is required.

- Option 3: Not compulsory – Not correct, as the drawee’s acceptance is usually needed.

- Option 4: Not necessary – Not correct, except in rare cases.