challenge: During an annular solar eclipse, why does the Sun appear like an annulus (ring) to viewers on Earth?
  
  A. Because of the Earth's axial tilt during the eclipse
  B. Due to the Moon's position at its descending node of orbit
  C. As a result of the Moon's apparent diameter being smaller than the Sun's
  D. Because the Moon's apparent diameter is larger than the Sun's
  Answer: 