Atruck driver makes deliveries across the country. he records the number of miles he has traveled in relation to the number of hours he has driven in the table below.

what is the unit rate of change for the information in the table ?

time
(hours)
( 7) (9) (11) (13) (15)

distance
(miles)
(448) (576) (704) (832) (960)

a. 68 miles per hour

b. 72 miles per hour

c. 69 miles per hour

d. 64 miles per hour