Which of the following involves an endothermic reaction? A. lighting a Laboratory burner B. pens converting sunlight into chemical energy C. burning propane D. using a chemical hand warmer

An endothermic reaction is one in which takes in heat energy.

If it gives out heat energy it is an exothermic reaction.

Option B Pens converting sunlight into chemical energy is the answer.

Because it absorbs the heat energy of the sun in order to do that.

By the way what is that Pens. Never heard of it.

Other options there would give out heat. Only B takes in heat.