Modulation is required to
a) distinguish different transmissions
b) ensure that the information may be trans mitted over long distances
c) allow the information accessible for different people

Options

A. a & b are true
B. b & c are true
C. c & a are true
D. a, b & c are true

Answer

**Step-by-Step Solution:**

1. **Understanding Modulation**: Modulation is the process of varying a carrier wave in order to transmit information. This is essential in communication systems to ensure effective transmission of signals over long distances.

2. **Analyzing the Options**:
- **Option a**: "Distinguish different transmissions" - Modulation allows different signals to be transmitted simultaneously over the same channel by assigning different frequencies to each signal. This means that the modulation process helps in distinguishing between different transmissions.

- **Option b**: "Ensure that the information may be transmitted over long distances" - Low-frequency signals, such as audio signals, cannot travel long distances without significant loss. By modulating these signals onto a higher frequency carrier wave, the transmission can cover larger distances with minimal loss.

- **Option c**: "Allow the information accessible for different people" - Modulated signals can be transmitted to various receivers, allowing multiple people to access the same information. This is especially true in broadcasting scenarios where the same signal is sent to many receivers.

3. **Conclusion**: Since all three statements (a, b, and c) are true regarding the necessity of modulation, the correct answer is that modulation is required for all the mentioned reasons.

**Final Answer**: All of the above (a, b, and c) are correct.

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