[单选题]
A spaceship takes a nonst.:qe ;69g p2mnp nzppskz.uj;+scqu;a ,hjz 0 op journey to a planet and returns in 10 hours according to 0;qsuujhac+.k, zj; z a clock on the spaceship. If 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. $17 \; h$
