Myla had her hair styled at many different salons. She graphed the total cost of each hair style and the amount of money she left as a tip.

Which of the following describes the rate at which the amount of the tip changed?
A.
It increased by $5 for every $1 increase in the cost of the hair style.

B.
It increased by $1 for every $2 increase in the cost of the hair style.

C.
It increased by $1 for every $1 increase in the cost of the hair style.

D.
It increased by $1 for every $5 increase in the cost of the hair style.