To fill in the term that best completes the statement, we have to realize the relationship between work and energy.
In general, the work done by an object on any other object is manifested as the change in the energy level of the two objects.
Thus, energy is transferred from one object to the other object when work is done by the former on the latter.
Therefore, term that best completes the statement is energy.
Hence our complete statement will be:
"Work transfers energy between objects".