Demand for Barbara Streisand CDs Is Equal to Q_s =

Demand for Barbara Streisand CDs is equal to Q_s = P^2.50_sI^1.80P^0.60_c, where Q_s is the number of CDs, P_s is the price of a Streisand CD, I is per capita income, and P_c is the price of a Karen Carpenter CD.Streisand and Carpenter CDs

A) are inferior goods.
B) are substitutes.
C) are complements.
D) have diminishing returns to scale.
E) are not as good as the original 8-track tapes.