Which of the contexts below could not be modeled by a linear function?

A car depreciates at a rate of 8.3% per year.

Snow was falling at a rate of 2.25 inches per hour.

A sunflower was growing at a rate of 1.5 inches per week.

A taxí charges a flat fee of $2.50 for pick-up, then an additional fee of $3.75 per
mile.