How Can We Tell That Some Stars Are Relatively Close

Multiple Choice

How can we tell that some stars are relatively close to us in the sky?

A) Some stars are occasionally eclipsed by the moon, so they must be nearby.
B) Some stars vary in brightness caused by sunspots we can see because they are so close.
C) Some stars appear to be extremely bright and must therefore be very close to us.
D) Some stars appear to move periodically back and forth against the background stars because of Earth's movement around the sun.