Select the following definitions $($or partial definitions$)$ to the appropriate term. Each term may be used once or not at all.

$\backslash$table$[[$Definition $($or Partial Definition$),$Term$],[$a$.,$An institution charged with responsibility for avoiding overissuance of a corporation's stock,$],[$b$.,$An institution responsible for maintaining detailed records of shareholders and handling changes of ownership of$,],[$c$.,$Cash or other assets set aside for the retirement of a debt,$],[$d$.,$Shares of its own stock acquired by a corporation for the purpose 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.,$]]$