Suppose the Demand Function for Cable TV Service Is Given

Suppose the demand function for cable TV service is given by Q_CTV = 15 - 0.25xP_CTV + 0.0005xM + 0.3xP_STV,where Q_CTV is the quantity of cable TV demanded (thousands of households) ,P_CTV is the price of cable TV,M is income and P_STV is the price of satellite TV service.If consumers' income is $50,000 and the price of satellite TV service is $90,then the demand curve for cable TV would be given by

A) Q_CTV = 17 - 0.25xP_CTV
B) Q_CTV = 67 - 0.25xP_CTV
C) Q_CTV = 15 - 0.25xP_CTV + 0.0005xM + 0.3xP_STV
D) Q_CTV = 13 - 0.25xP_CTV