Question

photosynthesis is an example of
an exothermic reaction.
an endothermic reaction.
a reaction that gives off heat.
a reaction that emits energy.

Explanation:

Photosynthesis is a process in which plants use light energy (from the sun) to convert carbon dioxide and water into glucose and oxygen. Endothermic reactions are those that absorb energy (in this case, light energy). Exothermic reactions release heat/energy. Since photosynthesis absorbs energy (it doesn't give off heat or emit energy in the sense of exothermic reactions), it is an endothermic reaction.

Answer:

an endothermic reaction.