Alandowner and a contractor entered into a written contract under which the contractor agreed to build a building and pave an adjacent sidewalk for the landowner at a price of $200,000. later, while construction was proceeding, the landowner and the contractor entered into an oral modification under which the contractor was not obligated to pave the sidewalk, but still would be entitled to $200,000 upon completion. the contractor completed the building. the landowner, after discussions with his landscaper, demanded that the contractor pave the adjacent sidewalk. the contractor refused. has the contractor breached the contract? (a) no, because the oral modification was in good faith and therefore enforceable.(b) yes, because a discharge of a contractual obligation must be in writing.(c) yes, because the parol evidence rule bars proof of the oral modification.(d) yes, because there was no consideration for the discharge of the contractor’s duty to pave the sidewalk.