Modulation is the phenomenon of :

Options

A. superimposing the audio frequency signal over a carrier wave
B. separting the audio frequency signal from the carrier wave
C. separting carrier wave from the modulated wave
D. any of (1), (2), (3) above

Answer

### Step-by-Step Solution:

1. **Understanding Modulation**: Modulation is a technique used in electronics and telecommunications. It involves varying one or more properties of a periodic waveform.

2. **Identifying the Components**: In modulation, we typically have two signals:
- **Modulating Signal**: This is the signal that contains the information to be transmitted.
- **Carrier Wave**: This is a higher frequency signal that carries the information from one place to another.

3. **Process of Modulation**: The modulating signal is combined with the carrier wave. This process allows the information contained in the modulating signal to be transferred effectively over long distances.

4. **Purpose of Modulation**: The main purpose of modulation is to enable the transmission of information over various media (like air, cables, etc.) by superimposing the modulating signal onto the carrier wave.

5. **Conclusion**: Therefore, modulation is the phenomenon of varying the properties of a carrier wave with the information signal to facilitate effective communication.