Avery leaves her house at 6:00 a.m. to go for a 9-mile run and returns to her house at 6:30 a.m. Describe the distance d (in miles) Avery runs as a linear function of her run time t (in minutes).
A) d = 0.3t
B) d = 0.2t + 6
C) d = 0.6t - 9
D) d = 0.4t + 9