Which of the following best describes the Milky Way Galaxy?
A) a spiral galaxy with a disk about 100,000 light-years in diameter and containing between 100 billion and 1 trillion stars
B) a spiral galaxy with a disk about 1 billion kilometers in diameter and containing between 100 million and 1 billion stars
C) a spiral galaxy with a disk about 100,000 light-years in diameter and containing about 100,000 stars
D) a spherically shaped collection of stars including our solar system and about a dozen other solar systems, stretching about 4 light-years in diameter
E) a spherically shaped collection of about 1 million stars that is about 100 light-years in diameter
Answer: A