*Question T0A02:
What health hazard is presented by electrical current flowing through the body?*  

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

### AI Response: (may contain errors)  

The correct answer to the question about health hazards presented by electrical current flowing through the body is:

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

### Explanation of the Correct Answer:
Electrical current can indeed cause multiple health hazards, which include:

- **Heating Tissue (Choice A)**: When current flows through the body, it can generate heat due to the resistance of body tissues. This heating can lead to burns or damage to internal organs.

- **Disruption of Electrical Functions of Cells (Choice B)**: The human body relies on electrical signals for many functions, including muscle contractions and nerve impulses. An external electrical current can interfere with these signals, potentially leading to dysfunction.

- **Involuntary Muscle Contractions (Choice C)**: Electrical current can stimulate muscles, causing them to contract involuntarily. This can be dangerous, especially if it affects the heart or other critical muscles.

Since all these effects can occur due to electrical current, the correct answer is indeed **D: All these choices are correct**.

### Why the Other Choices Are Incorrect:
- **Choice A**: While it is true that electrical current can cause heating of tissue, this is only one aspect of the hazards presented. Therefore, it cannot be considered correct in isolation.

- **Choice B**: This choice highlights the disruption of electrical functions, but again, it only addresses one of the potential hazards.

- **Choice C**: This choice focuses on involuntary muscle contractions, which is a significant risk but does not encompass the full range of hazards associated with electrical current.

### Useful Rules of Thumb:
- **Ohm's Law**: Understanding Ohm's Law ($V = I \times R$) can help you grasp how current ($I$) interacts with resistance ($R$) in the body, leading to potential hazards.
- **Thresholds of Perception**: Currents as low as 1 mA can be felt, while currents above 10 mA can cause muscle contractions, and currents above 100 mA can be lethal.

By understanding these concepts, you can better appreciate the risks associated with electrical currents and prepare effectively for the exam.