Xiaowen uses two different ways as shown in the figure to carry the same batch of goods to the same car, of which the correct statement is () A.

A. The work done by overcoming gravity is W=Gh, that is, gravity times the height at which the heavy object is lifted, so the work done by overcoming gravity is the same no matter which method. So this item doesn't match the meaning of the question.

B, Figure B directly moves the heavy object, so the force used by people is equal to the gravity of the heavy object; Figure A uses an inclined plane to carry heavy objects. The inclined plane is a labor-saving and distance-saving machine.

Mechanical efficiency is the ratio of useful work to total work. Compared with not using machinery (Figure B), using machinery (the inclined plane of Figure A is a kind of machinery) brings more extra work, so the mechanical efficiency of Figure A is lower. This item is inconsistent with the meaning of the question.

D. according to the analysis of item c, the mechanical efficiency of a is lower than that of B.

So choose D.