Which of the Following Statements Is Not True About Discharge

Which of the following statements is not true about discharge by alteration?

A) If the parties' agreement is represented by a written instrument,a material,intentional alteration of the instrument by one of the parties discharges the other party.
B) If a party consents to an alteration or does not object to it after learning of it,even then he or she will be discharged.
C) Alterations by third parties without the knowledge or consent of either contracting party will affect the parties' rights.
D) Since contracts are created by mutual agreement,they are not allowed to be altered by either of the parties.