It shall be unlawful for any person, by use of the mails or any means or instrumentality of interstate commerce, directly or indirectly:

(a) To employ any device, scheme, or artifice to defraud,

(b) To make any untrue statement of a material fact or to omit to state a material fact necessary in order to make the statements made in the light of the circumstances under which they were made, not misleading, or

(c) To engage in any act, practice, or course of business which operates or would operate as a fraud or deceit upon any person, in, or in connection with (1) an offer to make or the making of, any transaction for the purchase, sale or delivery of silver bullion, gold bullion, bulk silver coins, bulk gold coins, or any other commodity pursuant to a standardized contract commonly known to the trade as a margin account, margin contract, leverage account, or leverage contract, or pursuant to any contract, account, arrangement, scheme, or device that serves the same function or functions as such a standardized contract, or is marketed or managed in substantially the same manner as such a standardized contract, or (2) the maintenance or carrying of any such contract.