[单选题]
What is the momentum : kzw)s.cms8-l1cocxin wkm5pxw4m+ac- rr7 r 1 3xf5ir$kg \cdot m/s$ of a proton when it is moving with a speed of 0.60c?
A. $1.2 \times 10^{-19} \; kg \cdot m/s$
B. $1.5 \times 10^{-19} \; kg \cdot m/s$
C. $3.0 \times 10^{-19} \; kg \cdot m/s$
D. $3.8 \times 10^{-19} \; kg \cdot m/s$
