a. Producer Expectations

Reason: The producer expectation of the demand and price of the good forms an important determinant of supply. If the producers expect the demand of the product and price of the product to increase in the future, they will alter their level of supply in the market accordingly. Similarly when the producers expect the demand and price of the good to fall down in the future, they would be unwilling to supply more in the future and rather increase there supply in the current period. The producers get guided by the profit motive to increase the supply of goods. This profit motive is served when the price of the good registers an increase. Hence producer's expectation about prices and profits will make them alter the level of supply.