Final answer:
In a defined benefit plan, the number of eligible employees that must be covered by the plan depends on the requirements or regulations set by the employer.
Step-by-step explanation:
In a defined benefit plan, employers guarantee specific retirement benefits to employees, typically based on factors such as years of service and salary. The question asks how many eligible employees must be covered by the plan. To answer this, we need to know the requirements or regulations related to the plan. Without that information, it is not possible to determine which option is correct.