Which of the following can be used to enter a transceiver’s operating frequency?

Modern transceivers typically allow you to tune or enter the desired operating frequency using a main tuning dial, known as the VFO (Variable Frequency Oscillator) knob, or by directly typing the frequency into a numeric keypad on the face of the radio or the microphone. The other options serve different purposes. CTCSS and DTMF encoders are used for sending sub-audible tones for repeater access or telephone-style touch tones over the air. Automatic Frequency Control (AFC) keeps a receiver tuned to a drifting signal, but it is not a method for the user to manually enter a new frequency.