An investment banking department of a brokerage firm often receives material nonpublic information that could have considerable value if used in advising the firm's brokerage clients. In order to conform to the Code and Standards, which one of the following is the best policy for the brokerage firm? a. Permanently prohibit both purchase and sell recommendations of the stocks of clients of the investment banking department. b. Establish physical and informational barriers within the firm to prevent the exchange of information between the investment banking and brokerage operations. c. Prohibit purchase recommendations when the investment banking department has access to material nonpublic information but, in view of the fiduciary obligation to clients, allow sale of current holdings. d. Monitor the exchange of information between the investment banking department and the brokerage operation