Which of the following is NOT a criterion for determining a participant's benefit amount?

The correct choice reflects that automatic enrollment does not directly influence the calculation of a participant's benefit amount. Automatic enrollment typically pertains to the default process by which employees are enrolled in retirement plans unless they opt out. While it facilitates participation in retirement savings, it does not affect the formula or criteria that outline how much benefit a participant will receive upon retirement.

In contrast, the other criteria listed play significant roles in determining benefit amounts. For instance, the participant's age at retirement can influence the payout, as benefits may behave differently based on whether one retires early, at full retirement age, or delays retirement. The type of benefit selected, such as a lump sum or an annuity, also directly impacts the amount received. Lastly, the vesting process determines the portion of employer contributions to which a participant is entitled based on their years of service, further affecting the overall benefit amount. Understanding these distinctions helps clarify the processes involved in retirement planning and the impacts of various decisions on retirement benefits.