What does a contribution refer to in a retirement plan context?

In the context of a retirement plan, a contribution specifically refers to the money that an individual adds to their retirement savings account. These contributions can come from various sources, including employee payroll deductions or employer matching funds, and are essential for building the future financial security of the retiree. Contributions made to accounts like 401(k)s or IRAs can also come with tax advantages, making them a vital part of retirement planning.

The other options describe different aspects of a retirement account but do not accurately define a contribution. Earnings accrued in an account represent the growth of the investment over time but do not pertain to the act of adding funds. The total balance in an employee's account reflects the summation of contributions and earnings but is not a definition of contributions themselves. Withdrawals denote the process of taking money out of an account, which is the opposite of contributing to it. Thus, the correct answer focuses on the act of adding money, which is fundamental to retirement savings.