Use the Following General Linear Demand Relation $Q _ { d } = 100 - 5 P + 0.004 M - 5 P _ { R }$

Multiple Choice

Use the following general linear demand relation: $Q _ { d } = 100 - 5 P + 0.004 M - 5 P _ { R }$ where P is the price of good X,M is income,and $P _ { R }$ is the price of a related good,R.From the demand function it is apparent that related good R is

A) normal.
B) inferior.
C) a substitute for good X .
D) a complement for good X.