Which duty is NOT included in the National Association of REALTORS $($NAR$)$ Code of Ethics Duties to Clients and Customers?

$($a$)$ REALTORS keep entrusted funds of clients and customers in a separate escrow account.

$($b$)$ REALTORS make sure that contract details are spelled out in writing and that parties receive copies.

$($c$)$ REALTORS cooperate with other real estate professionals to advance their clients' best interests.

$($d$)$ REALTORS must complete $14$ hours of continuing education every two years following the first license renewal.