Which of the following applies when two stations transmitting on the same frequency interfere with each other?

In amateur radio, no single operator or group has an absolute right to a specific frequency. When two stations find themselves interfering with each other, the FCC expects operators to act courteously and negotiate the continued use of the frequency. This might mean one station agrees to move to a clear frequency, or both agree to take turns. Using subaudible tones (like CTCSS) is a common distractor here, but tones only mute the receiver; they do not prevent actual RF interference if both stations transmit at the same time. You should never just ignore interference, and there is no rule requiring both stations to abandon the frequency completely.