Which of the following molecules do autotrophs require for photosynthesis?

Autotrophs, such as plants, algae, and certain bacteria, require carbon dioxide for photosynthesis. During this process, they convert light energy, usually from the sun, into chemical energy stored in glucose. Carbon dioxide acts as a key raw material, combining with water in the presence of sunlight and chlorophyll to produce glucose and oxygen as byproducts. This transformation is crucial for life on Earth, as it not only fuels the autotrophs themselves but also contributes oxygen and organic materials that are essential for heterotrophs, which depend on autotrophs for their energy needs.

The other molecules listed do not serve as primary inputs in the photosynthetic process. Oxygen is produced as a byproduct rather than consumed during photosynthesis. Glucose, while an important product of the photosynthesis process, serves as an energy source for the plant rather than a requirement for the process itself. Ammonia is not used directly in photosynthesis and is more relevant to nitrogen metabolism and other biochemical processes. Thus, carbon dioxide is the essential molecule for photosynthesis among the options provided.