Which of the following is an advantage of a 401(k) plan?

A significant advantage of a 401(k) plan is that employers can match the contributions of their employees. This matching contribution can significantly enhance the total savings for retirement, essentially providing free money that helps employees build their retirement funds more rapidly. The employer contributions are often based on a percentage of the employee's contributions, which incentivizes employees to save more for their retirement. This feature not only encourages employees to participate in the plan but also helps to foster a culture of saving for the future.

The other options present various aspects of a 401(k) but do not accurately reflect its advantages. For instance, while it is true that some withdrawals might come with tax advantages, the entirety of a 401(k) is not tax-free when withdrawn. Additionally, while there are specific circumstances under which funds might be used for a house down payment without penalty, these are limited and not a generalized advantage of the plan. Lastly, while investments can experience gains in a 401(k), they are subjected to market risks and can indeed lose value, which does not align with the assertion that the invested money will not lose money.