The sum of Kinetic Energy and Potential Energy is always constant provided:

Explanation

The principle of conservation of mechanical energy states that the total mechanical energy in a system remains constant when only conservative forces are acting. Conservative forces, like gravity, do not dissipate energy as heat, whereas non-conservative forces, such as friction, do. Therefore, in the presence of friction, mechanical energy is not conserved as it is converted into other forms, primarily heat. This makes Option B correct, as it specifies the absence of friction. Other options incorrectly assume that energy conservation is possible with friction or provide contradictory or non-applicable scenarios.