For the year ended September 2015 nominal retail sales were $78bn. For the September 2016 year they were $82bn. From September 2015 to September 2016 retail prices rose by 0.9 percent. The change in real retail sales was

Select one:

a.

4.2 percent.

b.

0.9 percent.

c.

5.1 percent.

d.

6.0 percent.