Stephen had a 10:00\:a.m. appointment 60\:km from his home. He averaged 80\:km/h for the trip and arrived 20 minutes late for the appointment. At what time did he leave his home?
Answer Choices
A. 9:35\:a.m.
B. 9:15\:a.m.
C. 8:40\:a.m.
D. 9:00\:a.m.
E. 9:20\:a.m.