Explanation:

- Void: An agreement is void if it is based on an impossibility. Parallel lines never intersect; hence, the agreement is based on an impossible event and is void.

- Voidable: Agreements that are valid and enforceable but can be invalidated by one party are voidable. This situation doesn’t apply here.

- Valid: For a contract to be valid, it must be possible, legal, and involve mutual consent. An agreement based on impossible events isn't valid.

- Illegal: An agreement is illegal if it involves unlawful actions. This agreement isn't illegal; it's just based on an impossibility.

Void: The agreement is void since it's based on an impossible event.