Final answer:
Under a cafeteria plan, pretax contributions to a 401(k) are subject to FICA taxes which include the Social Security tax and the Medicare tax.
Step-by-step explanation:
Under a cafeteria plan, pretax contributions to a 401(k) are subject to FICA taxes. FICA stands for the Federal Insurance Contributions Act and includes two taxes: the Social Security tax and the Medicare tax. These taxes are deducted from an employee's paycheck to fund the Social Security and Medicare programs.