The Following General Linear Demand Relation $Q _ { d } = 680 - 9 P + 0.006 M - 4 P _ { R }$

Multiple Choice

the following general linear demand relation: $Q _ { d } = 680 - 9 P + 0.006 M - 4 P _ { R }$ where M is income and $P _ { R }$ is the price of a related good,R.From this relation it is apparent that the good is:

A) an inferior good
B) a substitute for good R
C) a normal good
D) a complement for good R
E) both c and d