According to the Law of Conservation of Energy, energy is neither created nor destroyed. It is an entity that's always existing in the environment. It takes different forms of energy. Among the choices, the best answer would be letter B. Chemical energy. The chemical energy originates from the energy within the muscles that are dormant. Once used, this chemical energy is transformed into mechanical energy by the action of pushing his foot on the ground.
Law of conversation says energy cannot be created or destroyed. Chemical energy is made from the muscles and transformed into mechanical energy when he pushes down.
It is false that deserts advance linearly, in easily mappable patterns. Deserts don't really have a pattern when they are advancing - there are so many ways they can do this.
