An ice cream truck sells ice cream between 2 pm and 10 pm each night in the summer. At the end of the night the driver calculates his profits and makes a graph to analyze the data. What is the average rate of change for the 1st hour to the 4th hour?
A. $24
B. $24 per hour
C. 8 hours
D. $8 per hour
20 points pizzazz help