*Question E7E07:
What is meant by the term “baseband” in radio communications?*  

*Correct Answer is  B: The frequency range occupied by a message signal prior to modulation*  

### AI Response: (may contain errors)  

In radio communications, the term "baseband" refers to the frequency range occupied by a message signal before it undergoes modulation. Let's break down the correct answer and the other choices.

### Correct Answer: 
**B: The frequency range occupied by a message signal prior to modulation**

- **Explanation**: Baseband signals are the original signals that contain the information to be transmitted, such as audio or data. These signals exist at their natural frequencies before any modulation process is applied to shift them to a higher frequency for transmission.

### Why the Other Choices are Incorrect:

- **A: The lowest frequency band that the transmitter or receiver covers**
  - This choice is misleading because it refers to the overall frequency range of the equipment rather than the specific characteristics of the message signal itself. Baseband is not defined by the lowest frequency but by the range of frequencies of the unmodulated signal.

- **C: The unmodulated bandwidth of the transmitted signal**
  - This option is incorrect because it implies a bandwidth concept rather than the frequency range of the message signal. Baseband refers to the actual frequencies of the message signal, not the bandwidth of the signal after modulation.

- **D: The basic oscillator frequency in an FM transmitter that is multiplied to increase the deviation and carrier frequency**
  - This choice is incorrect as it describes a specific function of an FM transmitter related to frequency modulation, not the concept of baseband. Baseband does not involve the oscillator frequency or modulation processes.

### Summary:
- Baseband signals are crucial in understanding how information is transmitted in radio communications. They represent the original message before modulation, which is essential for effective communication.

### Useful Rule of Thumb:
- Remember that baseband refers to the original signal's frequency range, while modulation shifts this signal to a higher frequency for transmission.