I don't fully understand this question. I believe it is a simple supply/demand response, but that seems a little basic. I am wondering what is going on in this graph.

3. Based on the graph below, and knowing nothing else about the Mystery Market, the mostly likely cause of the structural change between periods 1-3 and periods 4-6 is due to what market force? Price and Quantity in Mystery Market 2 1.8 1.6 1.4 1.2 1 Price 0.8 Quantity 0.6 0.4 0.2 0 1 2 W 4 5 6