A gardener transplanted a plant from an indoor pot to an outdoor garden. After 30 days, the plant's height was 18 centimeters. After 90 days, it was 29 centimeters. Write an equation to represent the plants growth where the x is the days and the y is the height of the plant.
A. y=1/6x+13
B. y=6x−162
C. x=1/6y+13
D. y=1/6x−13