A doctor sees patients in a fixed order. Patient A takes 30 minutes. Patient B takes 15 minutes. Patient C takes 45 minutes. Patient D takes 20 minutes. The doctor starts at 9:00 AM and sees them in the order A, C, B, D. At what time does the doctor finish with Patient B?
✓ Correct Answer: Option B
A: 9:00-9:30. C: 9:30-10:15. B: 10:15-10:30. D: 10:30-10:50. Doctor finishes B at 10:30 AM.