Which of the followings statement(s) regarding 403(b) plans is true?

1. Assets within a 403(b) plan may be invested in annuities.

2. Assets within a 403(b) plan may be invested in mutual funds.

3. All 403(b) plans must pass the ADP test

4. In certain situations, a participant of a 403(b) plan can defer an additional $25,000 (catch up) to a 403(b) plan in a single plan year