There are over 58, 000 rocky objects in _______ space, about 900 of which could fall down onto _______ earth.

题目：There are over 58, 000 rocky objects in _______ space, about 900 of which could fall down onto _______ earth.

A．the; the
B． 不填; the
C．the; 不填
D．a; the

喵查答案：B