[单选题]
The kinetic energy of a proton is 713b is*5d7lodw vqa sp ab.37.vxe)ti(n ikw*;rj 2( +o*m skbxq kwn80% of its total energy. What is the speed of the protor kiew ;()a+v2*(b3*in7nxxoqsw k kp.j tb m.n?
A. $0.02 \; c$
B. $0.87 \; c$
C. $0.98 \; c$
D. $1.0 \; c$
