Which of the following is NOT a valid reason for an insurer to contest a life insurance policy in its first two years?

A misstatement of age is a valid reason for an insurer to contest a life insurance policy, especially within the first two years. Insurers often have the right to adjust the benefits based on the insured's actual age if it was not accurately reported during the application process. If the age is misrepresented, it can affect the risk assessment and premium calculations made by the insurer.

On the other hand, fraud, material representation, and material concealment are more severe issues that can lead to a policy being contested. Fraud involves intentionally deceiving the insurer, while a material representation refers to providing significant false details that could influence the insurer's decision to issue the policy. Material concealment entails withholding important information from the insurer that could affect underwriting decisions.

In summary, misstatement of age does not provide a solid ground for contesting a policy when compared to these other issues, which directly contradict the fundamental assessment of risk in life insurance underwriting.