The graph plots price versus quantity.The horizontal axis is labeled quantity. The vertical axis is labeled price. The horizontal axis marks Q 1 and Q 2 from left to right. The vertical axis marks P 1 and P 2 from bottom to top. The graph shows a rising line labeled supply and two falling lines labeled D 1 and D 2. Point of intersection of supply line and D 1 is (Q 1, P 1) and point of intersection of supply line and D 2 is (Q 2, P 2). Refer to the above graph showing the market for a product. Which of the following could not explain the indicated increase in equilibrium price from P1 to P2? Multiple Choice an increase in consumer incomes an increase in production costs a decrease in the price of a complementary product an increase in the price of a substitute product