Explanation:

- Voidable Agreement: A contract that is valid and enforceable on the surface but may be rejected or voided by one party due to certain circumstances, such as misrepresentation or coercion.

- Illegal Agreement: An agreement that involves illegal activities and is not enforceable by law. This includes agreements to commit crimes like murder.

- Either (a) or (b): This suggests that the agreement could fall into one of the two previous categories, but not both.

- Both (a) and (b): Implies the possibility of being both voidable and illegal, which is usually not the case.

Correct Answer:

- Option: 2 - Illegal Agreement: