You can select from one of a series of BlackRock target date funds, which provide a mix of equities, fixed income, and real assets. The fund is matched to your expected retirement date, and the asset mix is automatically adjusted to become more conservative as you get closer to that date. Target date funds provide an investment solution that can reduce the complexity and stress of investing over time.
If you do not select a fund, your contributions will be invested in a default fund that is appropriate given the year you expect to retire under the plan. The default minimizes the risk of investment losses as you get closer to needing your retirement income.