*Question G7C08:
Which parameter affects receiver sensitivity?*  

*Correct Answer is  D: All these choices are correct*  

### AI Response: (may contain errors)  

To understand which parameters affect receiver sensitivity, let's break down each choice:

1. **Input amplifier gain (Choice A)**:
   - The gain of the input amplifier directly influences the ability of the receiver to detect weak signals. Higher gain means that weaker signals can be amplified to a level where they can be processed effectively, improving sensitivity.

2. **Demodulator stage bandwidth (Choice B)**:
   - The bandwidth of the demodulator stage affects how much of the signal's frequency range is processed. A narrower bandwidth can improve sensitivity to weak signals by reducing noise, while a wider bandwidth may allow more noise to enter, thus reducing sensitivity.

3. **Input amplifier noise figure (Choice C)**:
   - The noise figure (NF) of the input amplifier quantifies how much noise the amplifier adds to the signal. A lower noise figure means that the amplifier adds less noise, which improves the overall sensitivity of the receiver. 

Since all three parameters (gain, bandwidth, and noise figure) play a crucial role in determining how well a receiver can detect weak signals, the correct answer is:

**D: All these choices are correct.**

### Summary of Why Other Choices Are Incorrect:
- Each of the individual choices (A, B, and C) is indeed correct in its own right, but they do not encompass the full picture of receiver sensitivity. Therefore, selecting any one of them alone would be incomplete.

### Useful Formulas and Rules of Thumb:
- **Receiver Sensitivity** can often be expressed in terms of the minimum detectable signal (MDS) and is influenced by the following relationship:
  
  $$MDS = -174 \text{ dBm/Hz} + 10 \log_{10}(B) + NF + G$$

  where:
  - $MDS$ = minimum detectable signal level
  - $B$ = bandwidth in Hz
  - $NF$ = noise figure in dB
  - $G$ = gain in dB

This formula illustrates how all these parameters interact to determine the sensitivity of a receiver.