You have been given the task of designing a heat pack to relieve soreness in muscles by combining oxygen and iron. The more oxygen that is added to iron, the more it will heat up. Which of the following temperature changes would you be looking for? A. There will not be a reaction
B. An increase in temperature, showing an endothermic reaction
C. You should not expect a temperature change because this is a physical reaction
D. An increase in temperature, showing an exothermic reaction