[单选题]
The Feynman diagram shows two electrons ap+2 8:,;+zlp vaxv*wmw z+lswt ifko8 nproaching q v k*k831qszkeach other, interacting, and then leaving each other. What particle is being exchanged during the interaz831skvk q*k qction?
A. pion
B. virtual photon
C. neutrino
D. $W$ particle
