A severability provision in a cohabitation agreement or a premarital agreement provides that: a. The agreement contains the parties' entire agreement. b. If any provision of the agreement is held illegal or invalid, the remaining provisions will continue to be of full force and effect. c. The agreement binds the parties to its terms but does not bind their respective heirs and assigns. d. The agreement may be modified, amended, or rescinded at any time based on a mutual agreement of the parties