Under which of the following circumstances are one-way transmissions by an amateur station prohibited?

In the context of FCC regulations, 'broadcasting' is specifically defined as transmissions intended for reception by the general public. Because amateur radio is designed primarily as a two-way communications service between licensed operators, broadcasting is strictly prohibited on the amateur bands. However, it is a mistake to think that one-way transmissions are prohibited 'in all circumstances.' The FCC explicitly permits certain types of one-way transmissions, such as sending telemetry to space stations, controlling remote devices (telecommand), transmitting informational bulletins to other amateurs, and sending Morse code practice. Therefore, while many one-way transmissions serve a legitimate purpose in amateur radio, using your station to broadcast entertainment, music, or news to the general public is always forbidden.