Which of the following are required elements of the engagement letter? (1) Terms of propriety products, if presented (2) Compensation received by the CFP8 certificant (3) Any activity of other professionals consulted by the CFP certificant (4) Duties of the CFPS certificant and the client during all steps of the financial planning process a. (4) only b. (1) and (3) only c. (2). (3), and (4) d. (1). (2). (3), and (4)