The best evidence to support the student’s claim that “Life is possible because of the unique mixture of gases that cycle through the Earth’s spheres” would be:
a diagram illustrating how plants use carbon dioxide, water, and sunlight to produce food and oxygen gas.
This evidence directly relates to the cycling of gases (carbon dioxide and oxygen) and emphasizes the importance of these gases for life processes such as photosynthesis, which is crucial for sustaining life on Earth.