Which of the following are insulators?

Options

A. Brass, gold, steel
B. Tap, water, human body, silver
C. Moist air, human body
D. Pure water, air, mica

Answer

To determine which of the options contains insulators, we need to analyze each option based on the properties of the materials listed. Insulators are materials that do not conduct electricity well.

### Step-by-Step Solution:

1. **Analyze Option A: Brass, Gold, and Steel**
- Brass, gold, and steel are all metals.
- Metals are generally good conductors of electricity.
- **Conclusion**: This option does not contain insulators.

2. **Analyze Option B: Tap Water, Human Body, and Silver**
- Silver is a metal and is a good conductor of electricity.
- The human body contains water and electrolytes, which allow it to conduct electricity.
- Tap water typically contains minerals and impurities, making it a conductor as well.
- **Conclusion**: This option does not contain insulators.

3. **Analyze Option C: Moist Air and Human Body**
- The human body, as mentioned, conducts electricity due to water and electrolytes.
- Moist air contains water vapor, which can conduct electricity.
- **Conclusion**: This option does not contain insulators.

4. **Analyze Option D: Pure Water, Air, and Mica**
- Pure water is a poor conductor of electricity (a bad conductor).
- Air is also a poor conductor of electricity under normal conditions.
- Mica is a well-known insulator used in electrical applications.
- **Conclusion**: This option contains insulators.

### Final Answer:
- The correct option that contains insulators is **Option D: Pure Water, Air, and Mica**.