[单选题]
A distinctive feature of quarm3(1op .u:pnktl sj 3bksu/p/0mb2v h97buse,wa1 gt fv is that they
A. have zero rest mass.
B. have zero charge.
C. have fractional electric charge.
D. are always observed singly, since they do not readily interact with other particles.
Post time 2024-1-22 02:15:01