List any three human activities which would lead to an increase in the carbon dioxide content of air.

Explanation

### Step-by-Step Solution:

1. **Identify Human Activities**: The first step is to recognize that human activities can significantly impact the carbon dioxide levels in the atmosphere.

2. **List Deforestation**: One major activity is deforestation. Trees absorb carbon dioxide during photosynthesis, and when they are cut down, this process is disrupted, leading to higher levels of carbon dioxide in the air.

3. **Include Burning of Fossil Fuels**: Another significant activity is the burning of fossil fuels. This includes the combustion of coal, oil, and natural gas for energy, which releases carbon dioxide as a byproduct.

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