Why does knowing the velocity of a cloud in the disk of the Milky Way help astronomers figure out how far away it is? Choose one: A. Knowing the velocity allows us to see the cloud moving in real time. B. Knowing the velocity lets us use parallax to find the distance to the clouds. C. Knowing the velocity tells how a cloud is moving relative to us, and so this shows where it is in the galaxy's rotating disk. D. Knowing the velocity allows us to use Hubble's law to determine the distance