Suppose That, in a Closed System, There Is an Input

Suppose that, in a closed system, there is an input of energy as 1 kJ of light.The light energy is converted to glucose, then ATP, and finally to mechanical energy.Which statement about the amount of mechanical energy available is true?

A) There is 1 kJ of mechanical energy available to do work.
B) The amount of usable energy decreases with each conversion, so less than 1 kJ of energy is available for mechanical work.
C) All of the reactions involved are anabolic, so there is 0.25 kJ of mechanical energy available.
D) All of the reactions involved are exergonic, so the number of kilojoules of mechanical energy produced is greater than the 1 kJ input.
E) All of the reactions involved are endergonic, so without constant input of energy, no mechanical energy is produced.