The holding out rule is a regulatory requirement that prohibits registered individuals from using any title or designation other than their registration category when dealing with clients or potential clients. The purpose of this rule is to prevent misleading or confusing representations about the qualifications, roles, and responsibilities of registered individuals. According to Section 4.4 of National Instrument 31-103 Registration Requirements, Exemptions and Ongoing Registrant Obligations (NI 31-103), individuals who are registered to sell mutual funds must use the title “dealing representative” when holding out to clients or potential clients. Therefore, Ai Fen must prominently note “dealing representative” on her business card to comply with the holding out rule. The other options are not valid registration categories for selling mutual funds. Option B is a generic term that does not specify the type of securities that can be sold. Option C is a registration category for individuals who trade securities on behalf of an investment dealer. Option D is a professional designation that does not indicate registration status. References: [Holding Out Rule], [Registration Categories], [Registration Requirements, Exemptions and Ongoing Registrant Obligations]