The correct answer is 3, i.e. Potential energy. Mechanical energy is the sum of Kinetic energy and potential energy. ∘ Mechanical energy is the energy that is possessed by an object due to motion or its position. It is the total energy of an object that is used to do work. ∘It can be kinetic energy due to motion or potential energy due to the stored energy of position. ∘The potential energy is zero when the object is in motion and kinetic energy is zero when the object is at rest. ∘It is given as, M.E. = K.E. + P.E. M.E. $= ½ mv^2 + mgh$ Where m = mass of the object v = velocity of the object g = acceleration due to gravity h = height of an object ∘ Heat energy is the result of the movement of tiny particles called atoms, molecules, ions in solid, liquid and gases. The heat energy can be transferred from one object to another. This flow from higher temperature to lower temperature is called heat. ∘ When any substance participates in the chemical reaction to form another substance then the energy of a substance is called chemical energy. ∘ Energy is released during the process of nuclear fission or fusion is known as nuclear energy. It is used to produce electricity generation.