[单选题]
How fast would a rocket ship havctenr l+-f 9qxy- j eqrv*t:k/4;i;qj e tos)d7zdg.or:jngv 7+ *fw7 dlpr7 ovm- move to contract to half of its proper length (as obg mwj7pz*dvo gor:7 f7+sd).-vd rn7lserved by a stationary object)?
A. $0.50 \; c$
B. $0.65 \; c$
C. $0.78 \; c$
D. $0.87 \; c$
