Astro 120: Exam 3 Sample: answer key 1-b 11-c 21-d 2-d 12-a 22-d 3-d 13-d 23-c 4-c 14-c 24-a 5-c 15-a 25-b 6-e 16-e 26-b 7-c 17-d 8-b 18-d 9-d 19-b 10-c 20-b