Can an Employer Lower the Amount of Benefits It Offers

Can an employer lower the amount of benefits it offers its employees without violating the ADEA?

A) Yes, if the change is made in accordance with the Employee Retirement Income Security Act (ERISA) , which is the federal law governing employee benefits.
B) Yes, if the change is the same for all employees who are similarly situated regardless of age.
C) Yes, if different benefits are provided to younger and older workers based on a significant difference in the cost of providing the benefits to the older workers.
D) All of the choices are correct.