Energy can be lost in several ways during Lenore's action of pushing the box up the inclined plane. The most relevant option among the responses provided would be:
Friction between the box and the inclined plane.
This friction will convert some of the energy Lenore exerts into heat, which is a form of energy loss. Other potential sources of energy loss could include friction between her hands and the box, or even between her feet and the ground, but the most significant energy loss in this context is likely to come from the friction between the box and the inclined plane.