The answer is the one you are hovering your mouse over and have selected.
Function 1 has a greater rate of change. You can see this because throughout time, the amount of money in the account goes down $15.
This can be compared to Function 2. This function provides an equation in slope intercept form. The slope is 12, which means that the amount of money decreases by $12 each month.
Therefore, Function 1 has a greater rate of change because it changes by $15 instead of $12. I really hope this helps you! :))