Fitness uncle from Enshi, Hubei Province

(1) A directly acts on the object by hand, with the efficiency of100%; Second, using the inclined plane to do work on the object, at this time, it is necessary to overcome the friction to do extra work, and the efficiency is less than100%; So the mechanical efficiency of the two is not equal, so A is wrong.

(2) Party A and Party B lift the same object to the same height. According to W=Gh, they do equal useful work, so B is wrong and C is right.

(3) According to P=Wt, power is not only related to the amount of work done, but also related to the time of work done. The time of work done by both is unknown, so it is impossible to compare the power relationship between them, so D is wrong.

So choose C.