[单选题]
A spaceship takes a ns0 jt)( z+ipx;eab k/oonstop xu/q b1em9-i7u o5k/erebb0 h journey to a planet and returns in 10 hours according to a clock on the spaceship. If 1rhe 7q5uex 9bbi0om/beu- / kthe 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. $17 \; h$
