A college student collected data from a number of his classmates. He recorded the number of hours each spent watching television and sleeping each night. The scatter plot shows the data he gathered and the line of best fit.

Using technology, the student found the equation of the line of best fit is y = -x + 9.

Based on the equation for the line of best fit, how many hours of nightly sleep would a classmate likely get if she spent 6 hours watching television each night?

A.
3 hours
B.
15 hours
C.
6 hours
D.
7 hours