Explanation:

- Option 1: Valid and binding

An agreement not to plead the statute of limitations could, theoretically, be considered valid if both parties agree. However, it is often not legally enforceable due to overriding public policy considerations.

- Option 2: Void

Such agreements are commonly deemed void because they attempt to circumvent statutory time limits, which protect parties from having to defend against stale claims.

Correct Answer

- Option 3: Illegal

These agreements are not illegal, as they don't involve criminal activity. They simply have no legal effect.

- Option 4: Voidable at the option of the creditor

Normally, courts will not enforce these agreements, as they are void, not voidable. Hence, creditors have no discretion.