The Gomes family is on a road trip. On the first day, they drove a distance shown as 3 1/2 inches on a map. The actual distance that they drove was 245 miles. Which is the scale of the map?

A. 1 in : 3 1/2 mi
B. 1 in : 7 mi
C. 1 in : 70 mi
D. 3 1/2 : 70 mi