Final answer:
Carbon dioxide is consumed by plants during photosynthesis, where it is transformed into glucose and oxygen is released as a by-product. The correct option is b.
Step-by-step explanation:
Photosynthesis is a process that converts carbon dioxide and water into glucose and oxygen using sunlight. The role of carbon dioxide in this process is that it is consumed during photosynthesis, which, in the presence of sunlight, is transformed into energy-storing carbohydrates (glucose). Oxygen is generated as a by-product of this process. Thus, the correct answer to the students' question is b) Carbon dioxide consumption.