The Graph Shows the Total Sales in Thousand of Dollars $\frac{1}{3}$

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.

-10 to 40

A) $\frac{1}{3}$
B) $\frac{1}{4}$
C) 4
D) $\frac{2}{3}$