After leaving his house, Nate drove fifteen minutes to take his oldest daughter to the middle school and then drove ten minutes to take his two younger daughters to the elementary school. Next, Nate drove twenty-five minutes to work. If Nate arrived at work at 9:30 a.m., what time did he leave his house?
A. 8:10 a.m.
B. 8:20 a.m.
C. 8:30 a.m.
D. 8:40 a.m.