What is the BEST way to revise this sentence so that it conveys clear, concise ideas and does not change the meaning of the sentence?
Astronomy is the study of the sky that is all around us and the study of the mysterious objects in the vast reaches of space.
A. Astronomy is the study of the sky.
B. Astronomy is the study of mysterious objects.
C. Astronomy is the study of the sky that is all around us.
D. Astronomy is the study of the sky and the mysterious objects in it.
