[单选题]
How fast would a rocket ship have2ln)sv6 se6cq to move to contract to half of its prozxln : ww h2v .t-qvd2xq2v;p:per length (an;:2lqw dxhxq2 :2pzvtv- w. vs observed by a stationary object)?
A. $0.50 \; c$
B. $0.65 \; c$
C. $0.78 \; c$
D. $0.87 \; c$
