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

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 the Earth's movement around the Sun.

Question 2

Earth doesn't experience a solar eclipse every month because
 
  a. of unpredictable weather patterns.
  b. the moon always keeps its same side toward the Earth.
  c. the moon's position is not aligned with the Earth's orbit.
  d. its sometimes nighttime when the eclipse occurs.
  e. sometimes the moon is too far away.

Question 3

How do humans use their eyes to measure relative distance by parallax?
 
  a. By continuously focusing our eyes on distant objects we can determine distance.
  b. Since our eyes are separated the brain interprets the relative look angles of these eyes in terms of distance to the object viewed.
  c. Our eyes can measure the time it takes light to travel from an object and from this we get distance.
  d. By moving our heads from side to side our brain compares look angles from each of these positions to obtain the distance to the object viewed.

Question 4

If the Moon's orbital plane was aligned with the celestial equator we could
 
  a. have eclipses every month.
  b. never have eclipses.
  c. have eclipses only at solstice.
  d. have eclipses only at the equinoxes.

Question 5

Which stars always have large positive absolute magnitude?
 
  a. Stars of high luminosity.
  b. Stars of low luminosity.
  c. Nearby stars.
  d. Distant stars.
  e. Not enough information given.