Final answer:
Chemosynthesis differs from photosynthesis in that it does not require light, instead using chemical reactions to produce glucose. Option A) Light is what chemosynthesis has that photosynthesis does not.
Step-by-step explanation:
The process of chemosynthesis differs from photosynthesis primarily in that it does not require light as an energy source. Instead, chemosynthesis utilizes chemical reactions, often involving sulfur or methane, to produce glucose in the absence of sunlight. Specifically, what chemosynthesis has that photosynthesis does not is the ability to use inorganic molecules as an energy source instead of light.
To answer the student's question, the correct option is: A) Light. Photosynthesis requires light as a reactant, whereas chemosynthesis does not—chemosynthetic organisms derive their energy from chemical compounds like hydrogen sulfide, especially in environments with no light. Hence, glucose, carbon dioxide, and oxygen can all be involved in the process of chemosynthesis, but light cannot.
Photosynthesis, on the other hand, is a process where plants and cyanobacteria convert carbon dioxide, water, and light into glucose and oxygen, the latter being a byproduct.