Biking at 12 mph, it takes Kristen 1/4 hour to reach the train station to go to work. Kristen then takes the train to work, and it takes another 1/4 hour for her to get to work when the train travels 24 mph. How far does Kristen travel to work?
A.
9 miles
B.
8 miles
C.
33 miles
D.
19 miles