[单选题]
Particles that do not interact v/z/utfq pjz2; ia tsr*(yxqf *23nie s+ chhe strong force but do interact via the weak nuclear force (and presumably by the much weaker gravitation force) *n s*3(chfxq+sryi 2e are called
A. gauge bosons.
B. leptons.
C. baryons.
D. mesons.