What is the source of energy of all cellular activities in living organisms?
a.) atp
b.) lactic acid
c.) pyruvic acid
d.) glucose

Cells get energy by breaking down food molecules to release the stored chemical energy by a process called 'cellular respiration'.
During the process Oxygen is used to oxidize food, that oxidized food is known as glucose.

D.) glucose

A  reaction  in which  energy  is  released  to the surroundings is called an exothermic  reaction. in this type of  reaction  the enthalpy, or stored  chemical energy, is lower for the products than the reactants. when ammonium nitrate is dissolved in water,  energyis  absorbed  and the water cools.