Question: Under MSRB rules, a registered representative that has been given discretionary authority by a customer, needs specific customer authorization to purchase:________ A. Non-investment grade municipal bonds B. Bonds where a control relationship exists between the municipal broker-dealer and the issuer whose bonds are purchased C. Municipal bond unit investmentUnder MSRB rules, a registered representative that has been given discretionary authority by a customer, needs specific customer authorization to purchase:________ A. Non-investment grade municipal bonds B. Bonds where a control relationship exists between the municipal broker-dealer and the issuer whose bonds are purchased C. Municipal bond unit investment trusts D. Municipal bond option contracts