Final answer:
Universal life insurance is the policy that offers death benefit protection, cash value buildup, and the opportunity for premium flexibility. It differs from other types like ordinary whole life, variable life, and level term insurance in its flexibility, investment opportunities, and cash value component.
Step-by-step explanation:
The life insurance policy that combines death benefit protection, cash value buildup, and the opportunity for premium flexibility is D. Universal life insurance. Unlike ordinary whole life insurance which offers a fixed premium and benefit, universal life provides more flexibility to the insured by allowing them to adjust their premiums and death benefits within certain limits. On the other hand, variable life insurance allows for investment of the cash value in sub-accounts similar to mutual funds, and level term insurance provides death benefit protection without any cash value accumulation.