The Graph Shows the Total Sales in Thousand of Dollars $\frac{1}{2}$

Multiple Choice

The graph shows the total sales in thousand of dollars from the distribution of x thousand catalogs. Find the average rate of change of sales with respect to the number of catalogs distributed for the change in x.

-20 to 40

A) 2
B) $\frac{1}{2}$
C) $\frac{1}{4}$
D) 4