Which of the following statements about margin is true?
a) A Trading Participant may request from its Clients for margins above the minimum required by the Clearing House.
b) Each Client’s Open Positions must be marked to market daily and additional call for margins must be made if necessary.
c) Where margins are required, the Trading Participant must obtain a minimum initial margin and maintain the amount of minimum margins on all Open Positions.
d) A Trading Participant may Close Out any Open Position of a Client where the Client fails to comply with a demand for margin within 1 hour from the time of demand.