According to ERISA, which group of employees cannot be excluded from qualified plans?

The correct choice highlights that employees aged 21 or older with 1,000 hours worked cannot be excluded from qualified plans under ERISA (Employee Retirement Income Security Act). This provision is designed to ensure that employees who have reached a certain age and have worked a minimum number of hours are given access to retirement plans.

The age limit of 21 recognizes that younger employees may still be in early career stages and might not yet be eligible as they build their work history. The requirement of 1,000 hours worked further emphasizes the need for employees to show a substantial commitment to their job before they are included in such retirement plans, ensuring that plans benefit those who are actively participating in the workforce.

This framework aims to provide a balance between protecting employees' rights to retirement benefits while also acknowledging the employers' ability to manage their plans in a practical manner.