Which of the following is not a defined contribution plan subject to ERISA?

A Voluntary Employees' Beneficiary Association (VEBA) is indeed not a defined contribution plan that falls under the purview of the Employee Retirement Income Security Act (ERISA). VEBAs are typically established to provide benefits such as health care, disability, and death benefits to employees and their dependents, but they are funded on an as-needed basis rather than through defined contributions made by the employer or the employees.

In contrast, defined contribution plans, such as ESOPs (Employee Stock Ownership Plans), profit-sharing plans, and thrift plans, are structured so that there is a defined mechanism for both employer and employee contributions to accumulate over time in individual accounts, with the eventual distribution amount heavily dependent on the invested contributions and the investment performance of those contributions. Because those plans have established contribution formulas and are regulated by ERISA, they ensure certain protections for the participants.

VEBAs, being more geared towards welfare benefits and not structured to provide retirement income based on contributions, do not fit the traditional mold of defined contribution plans and are therefore excluded from ERISA's scope. This distinction clarifies why this option is the correct answer in identifying the plan that is not subject to ERISA requirements.