*Question E7F05:
How frequently must an analog signal be sampled to be accurately reproduced?*  

*Correct Answer is  B: At least twice the rate of the highest frequency component of the signal*  

### AI Response: (may contain errors)  

To accurately reproduce an analog signal, it must be sampled at a rate that meets the Nyquist criterion. This criterion states that:

- The sampling frequency must be at least twice the highest frequency component of the signal.

Thus, the correct answer is:

**B: At least twice the rate of the highest frequency component of the signal.**

### Explanation of the Correct Answer:
- **Nyquist Theorem**: This theorem states that to avoid aliasing and to accurately reconstruct the original signal, the sampling rate ($f_s$) must be at least twice the maximum frequency ($f_{max}$) present in the signal. Mathematically, this can be expressed as:
  
  $$f_s \geq 2 \times f_{max}$$

### Why the Other Choices are Incorrect:
- **A: At least half the rate of the highest frequency component of the signal**  
  - This is incorrect because sampling at half the rate would not capture enough information to reconstruct the signal, leading to aliasing.

- **C: At the same rate as the highest frequency component of the signal**  
  - This is also incorrect. Sampling at the same rate as the highest frequency would not provide sufficient data points to accurately reconstruct the waveform, again risking aliasing.

- **D: At four times the rate of the highest frequency component of the signal**  
  - While this is a safe sampling rate and would certainly avoid aliasing, it is not the minimum required rate. The Nyquist criterion only requires twice the highest frequency, making this option unnecessarily high.

### Summary:
To ensure accurate reproduction of an analog signal, always remember to sample at least twice the highest frequency component of that signal. This principle is fundamental in digital signal processing and is crucial for avoiding distortion and loss of information.