[单选题]
The net work done in movij gep he+a3z(o8e 9s5,fnu jh9ng an electron jfl b8e:bcztwzb0( 2.from point A, where the potential is -50 V, t.z b:tfjcb08z el( w2bo point B, where the potential is +50 V, is
A. $+1.6 \times 10^{-17} \; J$.
B. $-1.6 \times 10^{-17} \; J$.
C. zero.
D. none of the given answers