Which of these is best described as being on the arm of a spiral? a. the moon within earth's orbit b. earth within the solar system c. the milky way galaxy within the universe d. the solar system within the milky way galaxy

C. the Milky Way galaxy within the universe.

In the event that you gaze upward on a dim, crisp evening, endlessly from city lights, you may see a wide band of blackout light extending above you, stiller than a cloud and sparkle with thickly stuffed stars. Deciphered from the Ancient Greek as "Milky Way" for taking after spilled milk on the sky, that band of light is the focal point of our cosmic system.  

At its inside, encompassed by 200-400 billion stars and imperceptible to the human eye and by direct estimations, lies a super massive dark opening called Sagittarius A* or Sgr A* for short. The Milky Way has the state of a winding and pivots around its middle, with long twisting arms encompassing a marginally protruding plate.