[单选题]
What is the momentum iko/u8 vi2pu 3 0 n c*59uadb2kmk2fvtin $kg \cdot m/s$ 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. $3.8 \times 10^{-19} \; kg \cdot m/s$
