[单选题]
A spaceship takes a nons*8jv n:rq ar)btoqua g 7qyw+e)8p journey to a planet and returns in 10 hours according to a clock on the spaceship. If 8agqqew7 y)u+the speed of the spaceship is 0.80c, how much time has elapsed on the Earth?
A. $3.2 \; h$
B. $7.0 \; h$
C. $15 \; h$
D. $17 \; h$
Post time 2024-1-14 16:03:04