Which life insurance clause prevents questioning the validity of a contract after a specific time period?

The correct answer is the incontestable clause. This provision in life insurance contracts stipulates that after a certain period, usually two years, the insurer cannot contest the validity of the contract based on statements made in the application or claims of misrepresentation. This is a critical feature that provides policyholders with security and peace of mind, ensuring that, after this period, their policy is safe from being challenged, regardless of any issues that may arise regarding the original application.

The other clauses mentioned do not serve this purpose. The grace period clause allows a policyholder additional time to pay premiums without the risk of losing coverage, rather than addressing the validity of the contract itself. The renewal clause pertains to the continuation of a policy after its initial term, while the riders clause allows for additional coverage or options to be added to the policy, but neither of these relates to the contestability of the contract itself.