Question

what is the source of energy that drives photosynthesis?
sunlight
hydrogen ions
electrons
oxygen

Explanation:

Photosynthesis is a process in plants (and some other organisms) where they convert light energy into chemical energy. The key word here is "light" as the process starts with capturing light. Sunlight is the source of energy for photosynthesis. Hydrogen ions, electrons, and oxygen are involved in parts of the photosynthetic process but are not the initial energy source. Hydrogen ions are part of the proton - gradient in the electron - transport chain during the light - dependent reactions. Electrons are transferred during the light - reactions (e.g., from water splitting and through the electron - transport chain). Oxygen is a by - product of the light - reactions (from the splitting of water).

Answer:

sunlight