A scientist fills a glass container with water and places an aquatic plant inside the container, then closes the lid and places the container in direct sunlight. The scientist observes small bubbles on the surfaces of the plant's leaves on days 1 and 2, but no
bubbles on day 3. The scientist concludes that the bubbles were caused by photosynthesis. Which substance should be
added to the water in order for the bubbles to reappear? (1 point)