[单选题]
A distinctive featur8,c0og3ly4z qx: 3i 0jobew sne isr.,9v zpbgo1aib7 d;ly j 6*of quarks 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