Which of the following is a key feature of variable annuities?

Variable annuities are designed to offer policyholders the opportunity to increase their investment returns through market participation. This is achieved because the payouts from a variable annuity fluctuate based on the performance of the underlying investment options chosen by the policyholder. These options often include a variety of mutual funds or other investment portfolios. Therefore, the correct response highlights that the amounts received can vary, reflecting the gains or losses of the selected investments.

The other choices don't accurately describe variable annuities. They typically do not guarantee returns; instead, the returns are subject to market risk. Fixed payout amounts are characteristic of fixed annuities, not variable ones; fixed annuities state a predetermined payment throughout the payout phase. Lastly, immediate cash value is not a defined feature of variable annuities; while they can include surrender value options, immediate cash value applies more to immediate annuities that begin payouts right away, rather than those that may rely on investment performance over time.