Your score on this question is really not easy to get. I just calculated the answer to this question through the relevant examples in the futures market tutorial of the China Futures Association's national futures practitioners qualification examination book (basic knowledge part). The answer to this question should be A. 16440 yuan. The relevant explanations are as follows:

If you use the tutorial I mentioned above, if the answer to this question is A, then the question should be how much trading margin should be withdrawn from its settlement reserve account when the transaction is completed that day. If you ask how much trading margin should be withdrawn from the settlement reserve account when the transaction is completed on that day, the conditions of the question are not sufficient. Note that the withdrawal of reserve funds when the transaction is completed on the same day and the settlement on the same day are two different concepts.

The trading margin at the time of closing the transaction on the same day = the amount (or royalty) obtained by selling the option+the futures trading margin of the previous trading day-half of the hypothetical option = [46+864 * 5%-(864-850)/2] * 200 =16440 yuan.

Note: this question is obviously a virtual option, so the above calculation method will be used. In addition, it should be noted that the traditional option margin system uses the larger of these two calculated values as the option margin for each short-selling option, which are:

1. premium+option contract deposit-half of virtual option;

2. Royalty+half of option contracts deposit.