[单选题]
The Feynman diagram shows two electrons approachingnk r2cz9w ,ldj*j+k :c each other, wg5 dq ls.b:e:interacting, and t:qw :egd. 5slbhen leaving each other. What particle is being exchanged during the interaction?
A. pion
B. virtual photon
C. neutrino
D. $W$ particle
