What button must you press to transmit over the radio?

The correct answer is the transmit button, as this is the function specifically designed to send your voice or communication over the radio. In radio communication systems, the transmit button activates the transmitter, allowing your audio to be sent out over the chosen channel. This is a critical component of effective radio operation during emergency situations and in daily operations, ensuring that messages can be conveyed clearly and promptly.

The other options refer to functions that do not initiate transmission. The channel button is used to select or change the frequency or channel that the radio operates on, while the talk button may refer to a different model or brand-specific terminology but does not universally denote the transmission function. The VOX button enables voice-operated transmission but is designed for hands-free operation rather than direct manual transmission, which may introduce delays and could lead to missed communications in urgent scenarios.