Which of the following could affect an employee's eligibility for a benefit plan?

The employee's work schedule can significantly impact their eligibility for a benefit plan because many benefit programs have specific requirements related to the number of hours worked or the type of employment status (full-time versus part-time). For instance, some health insurance plans or retirement benefits may only be available to employees who meet a minimum threshold of hours worked in a given period. If an employee is scheduled to work fewer hours than required, they may not qualify for certain offerings as a result.

In contrast, the other options address different aspects that may relate to benefits but do not have the same direct influence on eligibility. For instance, while an employee's location might affect which benefits are available geographically, it doesn't change eligibility criteria per se. Similarly, the mere existence of a benefit does not imply that an employee's eligibility is affected; it may simply mean that they don’t have access to that specific benefit. Past participation in training programs generally does not influence benefit eligibility for most plans, as it is more related to professional development rather than benefits qualification.