The concepts of communication are
(a) mode of communication
(b) need for modulation
(c ) types of modulation
(d) detection of modulated wave

Options

A. a,b and c are true
B. b,c and d are true
C. c,d and a are true
D. a,b,c and d are true

Answer

To solve the question regarding the concepts of communication, we need to analyze each of the given options and determine which concepts are true. The question lists four concepts:

1. Mode of communication
2. Need for modulation
3. Types of modulation
4. Detection of modulated wave

Let's break down each concept step by step:

### Step 1: Mode of Communication
- **Explanation**: Modes of communication refer to the different ways information can be transmitted. Common modes include audio (sound), video (visual), and text (written). Each mode has its own characteristics and applications.
- **Conclusion**: This concept is true.

### Step 2: Need for Modulation
- **Explanation**: Modulation is necessary because the original signal may not have enough power to be transmitted over long distances. Modulation allows the signal to be adjusted so that it can effectively reach its destination without significant loss.
- **Conclusion**: This concept is true.

### Step 3: Types of Modulation
- **Explanation**: There are various types of modulation techniques used in communication systems, such as Amplitude Modulation (AM) and Frequency Modulation (FM). Each type has its own advantages and is used in different scenarios.
- **Conclusion**: This concept is true.

### Step 4: Detection of Modulated Wave
- **Explanation**: Once a signal is modulated for transmission, it is essential to detect the modulated wave at the receiving end to retrieve the original signal. This process is crucial for effective communication.
- **Conclusion**: This concept is true.

### Final Conclusion
Since all four concepts (a, b, c, and d) are true, the correct answer to the question is:
**Option D: a, b, c, and d are true.**

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