The unit of measure of work as used in the SI system is:

The unit of measure for work in the International System of Units (SI) is Joules. Work, in physics, is defined as the amount of energy transferred when a force is applied over a distance. Specifically, one Joule is equivalent to the work done when a force of one Newton displaces an object by one meter in the direction of the force.

Using this relationship, it becomes clear why Joules is the appropriate choice. Joules effectively quantify the work done in terms of both the force applied and the distance moved, making it a fundamental unit in understanding energy and work in various physical contexts.

The other options represent different quantities. Newtons measure force, kilowatts are a measure of power (rate of doing work), and foot pounds are a measure of work, but they are not part of the SI unit system. Therefore, Joules is the correct and standard unit for measuring work in SI.