Final answer:
Variable universal life insurance is the policy that provides both flexible premium payments and a variable investment component, combining features of both universal and variable life insurance.
Step-by-step explanation:
The type of policy that allows for a flexible premium and a variable investment component is d. variable universal life insurance. This kind of policy combines features of universal life insurance, which offers flexible premiums, with variable life insurance, which includes investment options. Cash-value life insurance policies like these offer both a death benefit and a cash value component that policyholders can invest in a variety of different accounts, similar to mutual funds. As the cash-value accumulates, it can be used by the policyholder for various purposes.