General exam question G4A09

WhyRF output is delayed after activating a transmitter's keying line to an external amplifier to allow time for the amplifier to switch the antenna between the transceiver and the amplifier output. External amplifiers use a relay to switch the antenna between the transceiver's direct output path and the amplifier's output, and that mechanical relay needs a brief moment to complete the switch before RF safely arrives, so the transmitter delays its RF output after asserting the keying line specifically to give the relay that time, answer C. It isn't there to shape key clicks, prevent overmodulation, or wait for a power supply to stabilize, those are unrelated concerns from unrelated circuits.