17 CFR 1.19: Prohibited trading in certain “puts” and “calls”.

No futures commission merchant or introducing broker may make, underwrite, issue, or otherwise assume any financial responsibility for the fulfillment of, any commodity option except:

(a) Commodity options traded on or subject to the rules of a contract market in accordance with the requirements of part 33 of this chapter;

(b) Commodity options traded on or subject to the rules of a foreign board of trade in accordance with the requirements of part 30 of this chapter; or

(c) For futures commission merchants, any option permitted under § 32.4 of this chapter, provided however, that a capital treatment for such options is referenced in § 1.17(c)(5)(vi).