The correct answer is:
b photosynthesis, where carbon dioxide and sunlight at Q and R are taken in and then converted into glucose and oxygen at S and T.
In the process of photosynthesis, plants take in carbon dioxide (CO₂) from the air and sunlight (light energy) and use these to produce glucose (a form of energy) and oxygen (O₂) as a byproduct. This process occurs primarily in the chloroplasts of plant cells, where chlorophyll captures sunlight.