What is a primary fuel?

Explanation

### Step-by-Step Solution:

1. **Definition of Primary Fuel**: A primary fuel is defined as a type of fuel that occurs naturally in the environment and is used in its natural form without any significant processing or alteration.

2. **Characteristics of Primary Fuels**:
- They are found in nature.
- They are utilized in the same state as they are extracted.
- They do not require extensive refining or processing before use.
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