Can u guys answer my question real quick pls

The owner of the plant nursery where you were tells you to fill 350 ml bottles from a 30 l from a fertilizer

Will give a: 122 b: 90 c: 48 d: 180

In order for the function to be linear, what must m be and why? m = 22 because the rate of change is 1. m = 20 because the rate of change is 3. m = 22 because the rate of change is -1. m = 20 because the rate of change is -3.