Rental Rental price price of DVD of DVD $10 31 $10 8 8 6 6 4 4 2 D2 2 D1 0 20 40 60 60 100 0 20 40 60 80 100 Quantity of DVDs (per weekend) Quantity

(Figure: Four Markets for DVDs) Examine the figure Four Markets for DVDs. If D1 or S1 is the original curve and D2 or S2 is the new curve, which of the graphs illustrates what may happen in the market for DVDs if there is an increase in the cost of a movie ticket at the local theater?

Please help and explain why the answer is so and how to distinguish how to know whether the demand line shifts or the supply curve shifts! We know it's either A or B but do not know for sure or why it is the answer. Thanks!