Which of the following allows employees to elect to reduce their current salaries by deferring amounts into a retirement plan?

The 401(k) plan is designed specifically to allow employees to defer a portion of their salary into a retirement account before taxes are applied. This means that employees can voluntarily choose to reduce their current salaries by the amount they wish to contribute to the 401(k), effectively deferring their income for later use in retirement. This deferral helps employees save for retirement while also reducing their taxable income in the year they make the contributions.

In contrast, IRAs (Individual Retirement Accounts) are typically opened and funded independently by the individual, and while they allow for contributions, they do not involve salary deferral directly from an employer's payroll. Defined contribution plans encompass a broader category that includes various retirement plans, where the employee's contributions might not necessarily involve a salary reduction mechanism. Keogh plans are specifically designed for self-employed individuals and small businesses and have different contribution structures compared to 401(k) plans.

Thus, the key characteristic of the 401(k) that sets it apart is the ability for employees to directly reduce their salaries through agreed-upon deferrals to support their long-term retirement goals.