Which of the Following Would Be a Valid Reason for an Insurer

Which of the following would be a valid reason for an insurer to contest a policy after the contestable period has ended?

A) The policyholder made a material misrepresentation in the application process.
B) The insurer's loss ratio is running higher than the insurer anticipated.
C) The applicant had someone else take the medical examination required for policy approval for her.
D) The policyholder concealed a material fact at the time of application.