Compare and contrast fossil fuels and the Sun as sources of energy.

Explanation

### Step-by-Step Solution:

1. **Definition of Sources**:
- Fossil fuels are natural substances formed from the remains of ancient plants and animals that have been subjected to heat and pressure over millions of years. Examples include coal, oil, and natural gas.
- The Sun is a massive star at the center of our solar system that emits energy in the form of sunlight, which can be harnessed as solar energy.

2. **Availability**:
- **Fossil Fuels**: The reserves of fossil fuels are limited. Once consumed, they cannot be replenished on a human timescale, making them exhaustible resources.
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