Open trade is not an alternative to trade used by the United States.
Open Trade Equity (OTE) is the equity in an open futures contract. The gain or loss is unrealized, and therefore subject to loss risk.
The correct answer between all the choices given is the last choice or letter D. I am hoping that this answer has satisfied your query and it will be able to help you in your endeavor, and if you would like, feel free to ask another question.