Which of the following is not a requirement for money purchase pension plans?

The choice highlighted is not a requirement for money purchase pension plans because one of the defining features of these plans is that they require a specific contribution formula that is definite and consistent, ensuring that contributions are made in a predetermined manner.

In contrast, adjustable employer contributions suggest flexibility and discretion, which contradicts the very purpose of a money purchase pension plan. These plans are designed to provide a fixed formula for employer contributions, giving employees certainty about their retirement savings based on defined contributions. Each participant having a separate account and the requirement of a definite contribution formula are fundamental aspects that ensure fairness and transparency in the management of the plan's assets. Thus, the specified contributions in a money purchase pension plan should not allow for employer discretion in the amounts contributed, making the notion of adjustable contributions irrelevant in this context.