19.當證券商的現金流出大於現金流入而產生資金缺口時，則該證券商應承作下列何種金融商品以彌補其資金缺口？ (A)附買回交易(Repurchase Agreement, Repo 或 RP) (B)附賣回交易(Reverse Repurchase Agreement, Reverse Repo 或 RS) (C)可轉讓定期存單(Negotiable Certificates of Deposit, NCD) (D)商業本票(Commercial Paper, CP)