A Decrease in the Equilibrium Price and Quantity in a Market

A decrease in the equilibrium price and quantity in a market would be caused by:

A) a decrease in the number of sellers in the market.
B) a decrease in the popularity of the product sold in the market.
C) an increase in the cost of producing the product sold in the market.
D) an increase in the price of a product that competes with the product sold in the market.