Question

question 21 which two processes both increase the amount of carbon dioxide in the atmosphere? a photosynthesis and cellular respiration b burning of fossil fuels and photosystem ii and i c spontaneous human combustion and photosynthesis d volcanic eruptions and cellular respiration

Explanation:

Photosynthesis uses carbon - dioxide, not releases it. Burning of fossil fuels releases carbon - dioxide. Photosystems I and II are part of photosynthesis and don't release carbon - dioxide. Spontaneous human combustion is a rare and not a significant source compared to others. Volcanic eruptions release carbon - dioxide from the Earth's interior and cellular respiration in organisms releases carbon - dioxide as a by - product.

Answer:

D. volcanic eruptions and cellular respiration