GMAT Sentence Correction (SC) | The stars, some of them at tremendous speeds, are in motion

The stars, some of them at tremendous speeds, are in motion just as the planets are, yet being so far away from the Earth that their apparent positions in the sky do not change enough for their movement to be observed during a single human lifetime.

(A) The stars, some of them at tremendous speeds, are in motion justas the planets are,yet being

(B) Like the planets, the stars are in motion, some of them