25 POINTS!!!!!! & WILL MARK BRAINLIEST- PLEASE HELP

A bathtub is being filled at a rate of 4 liters per minute. Can this situation be modeled with a linear function? Choose the answer that best describes this situation.

A.) Yes, this is a linear function because each input has one output.

B.) No, this is not a linear function because there is no such thing as a linear function.

C.) No, this is not a linear function because the rate of change is not constant.

D.) Yes, this is a linear function because the rate of change is constant.