The correct answer is option 4 - kg-metre/sec2.

Energy is the ability to do work, and it is measured in joules (option 1). The joule is the standard unit of energy in the International System of Units (SI). Option 2, watt-hour, is also a unit of energy. It is equivalent to the amount of energy consumed by a one-watt electrical device in one hour. Option 3, Newton-metre, is also a unit of energy. It is derived from the Newton, which is a unit of force, and the meter, which is a unit of distance. When a force is applied to an object and it moves through a distance, work is done, and the energy can be measured in Newton-metre.

However, option 4, kg-metre/sec2, is not a unit of energy but a unit of force. It is known as a newton and is used to measure the amount of force required to accelerate a one-kilogram mass at a rate of one meter per second squared. Alert - correct answer should be option 4 is not a unit of energy but a unit of force.