Modem is a device used for

Options

A. Converting digital signals to analog signals
B. Converting analog signals to digital signals
C. Either of these
D. None of these

Answer

### Step-by-Step Solution:

1. **Understanding the Modem**:
- A modem is a device that facilitates communication between digital devices over analog communication lines. The term "modem" is derived from two functions: modulation and demodulation.

2. **Definition of Modulation**:
- Modulation is the process of converting a digital signal (which is in binary form) into an analog signal. This is necessary because analog signals can be transmitted over traditional communication lines (like telephone lines).

3. **Definition of Demodulation**:
- Demodulation is the reverse process, where the analog signal received is converted back into a digital signal. This allows the digital device to interpret the information correctly.

4. **Functions of a Modem**:
- Therefore, a modem serves two primary functions:
- **Converting digital signals to analog signals** (modulation).
- **Converting analog signals to digital signals** (demodulation).

5. **Conclusion**:
- Based on the definitions and functions, we can conclude that a modem is used for both converting digital signals to analog signals and converting analog signals to digital signals.

### Final Answer:
A modem is a device used for converting digital signals to analog signals and converting analog signals to digital signals.