[单选题]
The length of a spaceship is 10v irh:lm3q.t, m when i/p 4 *hfiv u.5 ni(vklhd9q7jmt is at rest. If the spaceship travels by you with a speed of 0.70c, what length does it appear tv/9h m. *nqkfhl(45d iiujv7po you?
A. $5.5 \; m$
B. $7.1 \; m$
C. $12 \; m$
D. $18 \; m$
