Peanut butter and jelly are complements in consumption. Assuming that the supply curve of peanut butter is upward-sloping, if there is a decrease in the price of jelly, producer surplus in the peanut butter market:

will increase

Explanation:

Since both products are complements, a decrease in the price of one of them (in this case jelly) will increase the quantity demanded of both products, including the one whose price didn't change (peanut butter). An increase in the quantity demanded should increase the equilibrium price of peanut butter, which would result in an increase of supplier surplus.