Final answer:
A conservative force does work but does not remove mechanical energy; it only transforms it within the system, keeping the total energy unchanged.
Step-by-step explanation:
A conservative force does work on an object, but unlike non-conservative forces, it does not remove mechanical energy from the system. Instead, it converts mechanical energy from one form to another without any net loss. The total mechanical energy, which is the sum of kinetic and potential energies within a closed system, remains constant when only conservative forces are acting. If there are no external forces or the non-conservative forces do no work, the principle of conservation of mechanical energy applies. Thus, when analyzing forces and the work they do, a conservative force would correspond to Option 4: Does work but doesn't remove mechanical energy.