[单选题]
How fast would a roce3f pn2vi,bs,5*qlh a9bev +q8khl 6cket ship have to movesgpc, - :9r*l6 kk:axope tc)t to contract to half of its proper length (as observe:c,t * l9)g 6otrkp:pace skx-d by a stationary object)?
A. $0.50 \; c$
B. $0.65 \; c$
C. $0.78 \; c$
D. $0.87 \; c$
