[单选题]
The length of a spaceship is 10 m when it is at re41 d3/n/muj aku(b rvjst. If the ssyao)p.u.r r f/k/9jgpaceship travels by you with a speed of 0.70c, whr / kpjau.g/y9.sfo) rat length does it appear to you?
A. $5.5 \; m$
B. $7.1 \; m$
C. $12 \; m$
D. $18 \; m$
