Brian cannot remember whether he told his parents that he would be bringing his three roommates over for dinner on Sunday, or if he had just reminded himself to tell them. Which of the following statements best describes processing in this type of scenario?a. False memories regarding external sources account for the discrepancy. b. False memories regarding internal sources account for the discrepancy. c. Source monitoring can serve as a checkpoint. d. We are largely unable to distinguish between internal and external sources of information.