How do future expectations about the price of a good affect the present supply?

a. if the price is expected to increase and then decrease, most sellers will hold onto their supply until the decrease has occurred.
b. if the price of a related good is expected to increase, only a few sellers will hold onto their supply until the increase occurs.
c. if the price is expected to increase, many producers will hold onto their supply.
d. if the price is expected to decrease, many producers will hold onto their supply.