What does the MODEM do?

Options

A. Modulation only
B. Demodulation only
C. Both modulation and demodulation
D. Neither modulation nor demodulation

Answer

### Step-by-Step Solution:

1. **Understanding the Term "MODEM":**
- The term "MODEM" stands for "Modulator-Demodulator."
- It is a device used in communication systems.

2. **Function of a MODEM:**
- The primary function of a modem is to convert digital signals into analog signals.
- This conversion is necessary because analog signals can be transmitted over communication channels like telephone lines.

3. **Modulation Process:**
- The process of converting digital signals (which computers use) into analog signals (which can be transmitted over various media) is called modulation.
- This allows digital data to be sent over distances.

4. **Receiving End Functionality:**
- At the receiving end, the modem performs the reverse operation.
- It converts the received analog signals back into digital signals. This process is called demodulation.

5. **Conclusion:**
- Therefore, the modem serves two main functions: modulation (converting digital to analog) and demodulation (converting analog back to digital).
- The correct answer to the question is that a modem performs both modulation and demodulation.

### Final Answer:
A MODEM converts digital signals to analog signals for transmission and then converts them back to digital signals upon reception. Thus, it performs both modulation and demodulation.

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