$2.$ Emma told Renee, $$I will pay you $$4,000$ if you build the deck on these plans I am showing you within the next month.$$ Renee said, $$I agree. I will build that deck and be done no later than $30$ days from now.$$ What happened?

a$.$ They have a binding unilateral contract.

b$.$ They have a binding bilateral contract.

c$.$ They are still negotiating, there will be no contract until the deck is completed.

d$.$ There is a binding sales of goods contract under the U$.$C$.$C$.$