G1A06

Which of the following applies when the FCC rules designate the amateur service as a secondary user on a band?

1. AAmateur stations must record the call sign of the primary service station before operating on a frequency assigned to that station
2. BAmateur stations may use the band only during emergencies
3. CAmateur stations must not cause harmful interference to primary users and must accept interference from primary users
4. DAmateur stations may only operate during specific hours of the day, while primary users are permitted 24-hour use of the band

Pick an answer to check it.