The Estimated Demand for a Good Is $\hat { Q } = 4,800 - 16 P - 0.65 M - 1.5 P _ { R }$

The estimated demand for a good is $\hat { Q } = 4,800 - 16 P - 0.65 M - 1.5 P _ { R }$ where Q is the quantity demanded of the good,P is the price of the good,M is income,and $P _ { R }$ is the price of related good R.This good and good R are

A) complements since the coefficient on M is negative.
B) substitutes since the coefficient on M is negative.
C) complements since the coefficient on $P _ { R }$ is negative.
D) substitutes since the coefficient on $P _ { R }$ is negative.
E) none of the above