Refer to the accompanying figure. Suppose the solid line shows the demand for coffee. If coffee and tea are substitutes, and the price of tea falls, then you would expect:

A. an increase in the quantity of coffee demanded, but no shift in the demand curve.
B. a decrease in the quantity of coffee demanded, but no shift in the demand curve.
C. the demand curve to shift to D(B)
D. the demand curve to shift to D(A).

Answer: D