Select the following definitions $($or Partial definitions$)$ to the appropriate term. Each term may be used once or not at all. a$.$ an institution charged with the reponsibility for avoiding overissuance of a corporations' stock. b$.$ an institution responsible for maintaining detailed records of shareholders and handling changes of ownership of stock ownership. c$.$ cash of other assets set aside for the retiemend of a debt. d$.$ shares of its own stock acquired by a corporation for the purposed of being reissued at a later date. e$.$ the formal agreement between bondholders and the issuer as to the terms of the debt. f$.$ a system that allows electronic registration and transfer of securities in an investor's name.