Suppose that it is observed that the price of wheat falls and that the quantity sold also falls. From this we can deduce
◦ that the demand curve has shifted to the left, but we cannot deduce whether or not the supply curve has shifted.
◦ that the supply curve has shifted to the right, but we cannot deduce whether or not the demand curve has shifted.
◦ that the supply curve has shifted to the left, but we cannot deduce whether or not the demand curve has shifted.
◦ that the demand curve has shifted to the right, but we cannot deduce whether or not the supply curve has shifted.