[单选题]
The area under the curve, on a Force versus position (F vs. k pw+o8w n19wgi.zmc)(i8c ( sjlbt;e6wla h+ x) graph, representswclch ost ame;wg9i.(16li +(k88)zj +wnw bp x1o7nda-sfr 9 6wnmq/ 6n 7nmd1f9o rw-s/qxa
A. work.
B. kinetic energy.
C. power.
D. potential energy.
