Question

Warning triangles, flares, a vehicle's hazard lights, or emergency vehicles ahead, are all clues that you might be approaching ______________________.

Answer 1

All of the items you listed are signs that you might be approaching a collision scene.

Answer 2

All listed items indicate that we are approaching the scene of the collision. Flashes and warning triangles can also be seen when approaching the railroad crossing, but there are no vehicle's hazard lights, and vehicles for emergency cases, unless it's a collision, again. On parades can be seen such vehicles, if someone is tormented, but then there is no warning trianggls and flashers.  Answer is collision.