Final answer:
Boats over 6m and up to 9m as well as all human-powered vessels that are over 6m must have distress signals only as their visual signals.
Step-by-step explanation:
Boats over 6m and up to 9m as well as all human-powered vessels that are over 6m must have these visual signals:
- Distress signals only
- Distress signals and navigation lights
- Distress signals and sound signaling devices
- Distress signals, navigation lights, and sound signaling devices
According to the given options, the correct answer is (a) Distress signals only. Boats over 6m and up to 9m, and human-powered vessels over 6m, are required to have distress signals as their visual signals.