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.