Which of the following is good practice when choosing a transmitting frequency to answer a station calling CQ using FT8?

FT8 operates in highly structured 15-second time slots. When a station is calling CQ, they transmit during one time slot and listen during the next. To answer them, you must transmit during their listening period, which is the alternate time slot. Additionally, it is best practice to find a clear audio frequency on the waterfall rather than transmitting exactly on their frequency. By transmitting on a clear frequency, you avoid interfering with other stations trying to answer the same CQ, allowing the calling station's software to decode multiple callers simultaneously.