Morgan and Leigh spend a certain amount of money from their money box each month to buy plants. The table shows the relationship between the amount of money (y) remaining in Morgan's money box and the number of months (x):

Function 1

Number of Months

(x) Amount Remaining (in dollars)

(y)

1 50

2 40

3 30

4 20

The equation shows the relationship between the amount of money (y) remaining in Leigh's money box and the number of months (x):

Function 2:

y = −9x + 60

Which statement explains which function shows a greater rate of change?

a. Function 1 shows a greater rate of change, because Morgan spends $10 each month and Leigh spends $9 each month.

b. Function 1 shows a greater rate of change, because Morgan spends $10 each month and Leigh spends $60 each month.

c. Function 2 shows a greater rate of change, because Morgan spends $10 each month and Leigh spends $60 each month.

d. Function 2 shows a greater rate of change, because Morgan spends $50 each month and Leigh spends −$9 each month.