All of the Following Except One Are Reasons the Demand

All of the following except one are reasons the demand deposit multiplier may be smaller in practice than in theory.Which one is not a valid reason?

A) Banks do not want to hold excess reserves.
B) Some of the currency generated when bonds are purchased ends up outside of the banking system.
C) Banks sometimes hold more than their required reserves.
D) An open market operation may change the public's holding of cash.
E) All of the above are not valid reasons.