On average, every minute spent in tutoring increases a student's grade by 0.15 points. If the student already has a grade of 72, which equation describes the increase of the student's grade over time? O y = 0.15x + 72 O A = 72 (1+,015)^t Oy - 72x + 0.15 O A = 72 (1 + 0.0015)^t