[单选题]
The length of a spaceship /h:c5fxjfilf :x /8dfis 10 m when it is at rest. If the spa3kjyu (exfqu /j.(+1q zf fh.ms b(8,dfdp9s kceship travels by you wi91h/. pf8q sfz(j m(,.fkyf(d3j+su ku x edqbth a speed of 0.70c, what length does it appear to you?
A. $5.5 \; m$
B. $7.1 \; m$
C. $12 \; m$
D. $18 \; m$
