The General Linear Demand Function Below Is Used to Answer $Q _ { d } = a + b P + c M + d P _ { R }$

Multiple Choice

The general linear demand function below is used to answer questions :
$Q _ { d } = a + b P + c M + d P _ { R }$
where Q_d = quantity demanded, P = the price of the good, M = income,
$P _ { R }$ = the price of a good related in consumption.
-For the general linear demand function given above

A) $\Delta Q _ { d } / \Delta M = c$
B) d is the effect on the quantity demanded of the good of a one-dollar change in the price of the related good, all other things constant.
C) b is the effect on the quantity demanded of the good of a one-dollar change in the price of the good, all other things constant.
D) all of the above