G4A09

What is the purpose of delaying RF output after activating a transmitter's keying line to an external amplifier?

1. ATo prevent key clicks on CW
2. BTo prevent transient overmodulation
3. CTo allow time for the amplifier to switch the antenna between the transceiver and the amplifier output
4. DTo allow time for the amplifier power supply to reach operating level

Pick an answer to check it.