When a 401(k) plan does not pass the ADP test, which one of the following statements correctly describes one option to bring the plan into compliance with Section 401(k)?

a. The employer can make nonforfeitable contributions to the nonhighly compensated employees.

b. Highly compensated employees can defer until the following year the tax deduction equal to the excess in elective contributions.

c. Nonhighly compensated employees' deferrals can be recharacterized as after-tax contributions.

d. The plan can adopt a safe harbor, with the employer contributing either a matching contribution equal to 2% of compensation or a nonelective contribution of 3% of compensation.