[单选题]
How fast should a moving clock travel if it is toujiw/1sie .6 ryi2lu1 be observed by a staus6-/ts- g*mbgbc6n (4;q qi q hng1tytionary observer as running at on*csin6(;g qq ms 46ntyg q/th-b-gub1e-half its normal rate?
A. $0.50 \; c$
B. $0.65 \; c$
C. $0.78 \; c$
D. $0.87 \; c$
