*Question E0A06:
Why are there separate electric (E) and magnetic (H) MPE limits at frequencies below 300 MHz?*  

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

### AI Response: (may contain errors)  

To understand why there are separate electric (E) and magnetic (H) Maximum Permissible Exposure (MPE) limits at frequencies below 300 MHz, let's break down the reasons:

1. **The body reacts to electromagnetic radiation from both the E and H fields**:  
   - The human body can absorb energy from both electric and magnetic fields. At lower frequencies, the body interacts differently with these fields, necessitating separate limits to ensure safety.

2. **Ground reflections and scattering cause the field strength to vary with location**:  
   - At frequencies below 300 MHz, the wavelength is relatively long, and ground reflections can significantly affect the field strength. This variation means that both E and H fields need to be considered separately to accurately assess exposure.

3. **E field and H field radiation intensity peaks can occur at different locations**:  
   - Due to the nature of electromagnetic wave propagation, the peaks of electric and magnetic field intensities may not coincide spatially. This spatial variation requires separate limits to ensure that neither field exceeds safe levels.

4. **All these choices are correct**:  
   - Each of the above points contributes to the need for separate MPE limits for E and H fields at frequencies below 300 MHz. Therefore, the correct answer is D: All these choices are correct.

### Why the Correct Answer is Correct:
- **D: All these choices are correct**: Each choice provides a valid reason for having separate MPE limits. The combined effect of these factors ensures comprehensive safety standards.

### Why the Other Choices are Incorrect:
- **A, B, and C individually**: While each choice is correct on its own, they do not fully explain the need for separate limits unless considered together. The correct answer encompasses all these factors.

### Useful Formulas or Rules of Thumb:
- **MPE Limits**: The MPE limits are set to ensure that exposure to electromagnetic fields does not exceed levels that could cause harm. These limits are frequency-dependent and consider both electric and magnetic field strengths.

In summary, the need for separate MPE limits for E and H fields below 300 MHz is due to the body's interaction with these fields, variations in field strength due to environmental factors, and the spatial differences in field intensity peaks.