After leaving his house, Milton drove 25 minutes to take his oldest son to the middle school and then drove 15 minutes to take his two younger daughters to the elementary school. Next, Milton drove 35 minutes to work. If Milton arrived at work at 9:15 a.m., what time did he leave his house?
A. 8:00 a.m.
B. 8:10 a.m.
C. 8:20 a.m.
D. 8:30 a.m.