A pilot in flight sees a flashing red light from the tower. What does it mean?

1. 1Give way to other aircraft and continue circling
2. 2Cleared to land, but with extreme caution
3. 3Return to the starting point on the airport
4. 4The airport is unsafe, so do not land there

Source: Aeronautical Information Manual (FAA, Basic with Change 3, 9 July 2026), AIM 4-3-13 Traffic Control Light Signals (TBL 4-3-1), page 257