[单选题]
How fast would a rocket ship have to mobucypbsj+yp+p* :4 ,ave to contract to nhed:9e /crer u8:ys b;rcj1(half of its proper length (as observch nrs/;c ebd9: rr8eu1 :(yejed by a stationary object)?
A. $0.50 \; c$
B. $0.65 \; c$
C. $0.78 \; c$
D. $0.87 \; c$
