The correct answer is C. Reserves.
Mortality is the probability of death at a given age. Rebate is a refund of part of the premium paid if the insured person dies within a certain period of time. Management expenses are the costs of running an insurance company.
Reserves are funds that insurance companies set aside to pay out claims. They are not a factor in determining life insurance premiums because they are not directly related to the risk of death.
The other options are all factors that insurance companies consider when setting life insurance premiums. Mortality is the most important factor, followed by rebate, management expenses, and other factors such as the insured person’s age, health, and lifestyle.