Answer:
The correct answer would be - C. He is monitoring oxygen. The amount of gas released should be highest for the plant closest to the window and lowest for the plant farthest away from the window.
Step-by-step explanation:
The release of the oxygen gas in the process of photosynthesis depends on the rate of photosynthesis which depends on various factors such as carbon dioxide, light, and water. In this experiment air (carbon dioxide), water is constant only factors that are changed is light, and an increase in the light energy increase the rate of photosynthesis, and a decrease in the intensity of light depend decreases the rate of photosynthesis.
Thus any change in the light would affect the release of the oxygen gas which is measured through this experiment and gas released should be lowest for the plant farthest away from the windowand highest for the plant closest to the window.