One newton times one meter is equal to one Joule.
A newton is the unit of measurement for force, and a meter is the unit of measurement for distance. When force is applied over a distance, work is done, which is measured in Joules. Therefore, one newton multiplied by one meter results in one Joule of work done.
The other options listed (one water, one ampere, one kilogram) are not correct units of measurement for this calculation.