Under which condition can variable life policyholders buy additional units?

In a variable life insurance policy, policyholders have the flexibility to invest their cash values in various investment options, typically mutual funds or similar vehicles, that make up the separate account of the policy. When a policyholder decides to buy additional units, these units are specifically purchased from the funds that are part of the variable life insurance policy itself, which is known as the variable life fund.

This is fundamental to the concept of variable life insurance, as the cash value and death benefit fluctuate based on the performance of the investments in that fund. Therefore, the correct condition under which policyholders can buy additional units is to purchase them from the variable life fund, as it directly ties into the investment nature of this type of policy.

In contrast, the other options either misrepresent how the purchasing process for additional units works or limit the purchasing conditions inappropriately. For instance, units cannot be purchased from external investments or at fixed rates, as the nature of variable life insurance ties the investments closely to the policy's own fund performance.