increased level of oxygen increased level of carbon dioxide decreased ability to support life decreased ability to transmit light
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Which of the following best describes a change in Earth's atmosphere made by early photosynthetic life?
Possibilities:
- increased level of oxygen
- increased level of carbon dioxide
- decreased ability to support life
- decreased ability to transmit light

increased level of oxygen