[单选题]
The Feynman diagram shows two electrons approah *sj,wq1q+ivchrtfhm78c ,e5v2yi2 cy ing each other, interacting, and then leaving each8,vmr527hietcfy 2cy other. What particle is being exchanged during the interaction?
A. pion
B. virtual photon
C. neutrino
D. $W$ particle
