What does the term 'conspicuity' mean in the context of motorcycle safety, and how can a rider improve it?

1. The rider's ability to see hazards ahead; improved by using a clear visor
2. The legal requirement to sound a horn when approaching an intersection
3. The angle of a motorcycle headlight adjustment for night riding
4. How visible and noticeable the rider is to other road users; improved by wearing bright clothing, using headlights, and choosing visible lane positions