Which of the Following Would Cause an Increase in the Supply

Multiple Choice

Which of the following would cause an increase in the supply of peanut butter?

A) A decrease in the price of strawberry jam (assuming that peanut butter and strawberry jam are complements) .
B) An increase in the price of peanut butter.
C) An increase in the price of a product that producers sell instead of peanut butter.
D) An increase in the number of firms that produce peanut butter.