Fill in the following blanks with suitable words:
e) The least polluting fuel for vehicles is ………….

Explanation

To fill in the blank for the statement "The least polluting fuel for vehicles is ………….," we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Question**: The question asks for the least polluting fuel for vehicles.

2. **Understand the Options**: Common fuels for vehicles include petrol, diesel, and compressed natural gas (CNG).

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