[单选题]
An electric generator t-r4 y2h y6l :or*k hsiyk;zrv vrdhn. *j7x/a7rann eg ;fhmqt 2duump0p 6nm;wad(.n2 flh2* 9l/sforms
A. electrical energy into mechanical energy.
B. mechanical energy into electrical energy.
C. direct current into alternating current.
D. alternating current into direct current.
