(Figure: Price and Quantity of Vocal Lessons I) Suppose Lizzie

(Figure: Price and Quantity of Vocal Lessons I) Suppose Lizzie and Miranda are the only two customers in the market for voice lessons. Lizzie's demand is Q_M = 40 - 4P, and Miranda's demand is Q_V = 75 - 5P. Which panel represents the market demand for vocal lessons?

A) panel (a)
B) panel (b)
C) panel (c)
D) panel (d)