Which of the following is an example of a common clause in a purchase agreement? (a) the validity of the agreement depends on the seller's willingness to lower the (b) the validity of the agreement depends on the buyer's willingness to keep the asking price property as-is (c) the validity of the agreement depends on the buyer's ability to sell his or her own home (d) the validity of the agreement depends on the seller's ability prove he or she is buying another home