Figure 1 shows the market demand curve for blueberries.

The fall in the price of blueberries and the resulting increase in the quantity demanded could have been caused by:
a decrease in the price of a substitute product, such as strawberries.
an increase in the cost of producing blueberry Greek yogurt.
a reduction in the price of a complementary good, such as Greek yogurt.
perfect weather conditions during the growing season leading to a bumper harvest.