Explanation: A-2 emission is a type of amplitude-modulated telegraphy where a modulated continuous wave (MCW) is keyed on and off. The "chopper" in this context refers to a system that generates the audio frequency (AF) tone used for the modulation. * **A) As a double-keying system:** This is correct. One "keying" action is the rapid on/off cycling of the chopper to create the AF tone that modulates the carrier. The second "keying" action is done by the operator using a normal hand-operated key to turn the entire modulated signal (carrier plus tone) on and off, forming the Morse code characters. * **B) The automatic "chopper" turns the transmitter on and off at a rapid rate:** This describes how the chopper creates the audio tone. By rapidly interrupting a signal or modulating the carrier at an audio frequency, it generates the distinct tone characteristic of A-2. * **C) The other key is a normal hand operated key:** This refers to the operator's key, which is used to send the actual telegraphic information (Morse code) by keying the A-2 signal on and off. Since all three statements accurately describe the components and function of a "chopper" system producing A-2 emission, "All of the above" is the correct answer.