Corey Is the City Sales Manager for "RIBS," a National

Corey is the city sales manager for "RIBS," a national fast food franchise.Every working day,Corey drives his car as follows:
Miles
Home to office
20
Office to RIBS No.1
15
RIBS No.1 to No.2
18
RIBS No.2 to No.3
13
RIBS No.3 to home
30
​
Corey's deductible mileage is:

A) 0 miles.
B) 50 miles.
C) 66 miles.
D) 76 miles.
E) None of these.