The correct answer is B.

The statement that the payout time is known with certainty is incorrect in the context of traditional whole life insurance. The payout time, or the time when the sum insured will be paid out, is not predictable in a whole life insurance policy. This is because the payout is triggered by the death of the insured, which is an event that cannot be predicted with certainty. Therefore, while it is guaranteed that the sum insured will be paid out at some point (provided the policyholder continues to make the required premium payments), the exact timing of this payout is uncertain.

Choice A is incorrect. The beneficiary indeed receives the sum assured only on the death of the insured in a traditional whole life insurance policy. This is one of the defining characteristics of this type of policy.

Choice C is incorrect. It's true that in a traditional whole life insurance policy, premiums are paid throughout the lifetime of the insured. This ensures that coverage continues for as long as they live.

Choice D is incorrect. Premiums payable usually remain fixed throughout in a traditional whole life insurance policy, providing predictability and stability for policyholders.