[单选题]
The energy acquired 2vpmat,5v io n k)t jj /zftuc0*+:vd5by a4je kwy)v -qu) particle carrying a charge equal to that on the electron as a result of moving through a potential differen)-w) vqujke 4yce of one volt is referred to as
A. a joule.
B. an electron-volt.
C. a proton-volt.
D. a coulomb.
