Which of the following involves an endothermic reaction?
O
A. Using a chemical hand-warmer
O
B. Lighting a laboratory burner
O
C. Plants converting sunlight into chemical energy
D. Burning propane

C. Plants converting sunlight into chemical energy.

Explanation:

An "endothermic reaction" is a process whereby energy coming from the surroundings is being absorbed as heat. This activates the reaction to occur.  Since it absorbs the heat to start the reaction, then it can be classified as an endothermic reaction.

When plants convert sunlight into chemical energy, it absorbs the sunlight as a light energy on its chlorophyll. This is where photosynthesis occur. This then results to the chlorophyll reacting with the carbon dioxide, water and the energy which results to the production of oxygen and glucose.

So, this explains the answer.