The correct option is 3. either (a) or (b).

Explanation:

An arbitral award becomes enforceable under Section 36 of the Arbitration and Conciliation Act, 1996 when:

1. The time for making an application to set aside the arbitral award has expired, and no such application has been filed.
2. An application to set aside the arbitral award has been refused by the court.

Once either of these conditions is met, the arbitral award is considered final and enforceable, and it can be executed as a decree of the court.