The Net Gain or Loss on a Futures Contract for a Stock

The net gain or loss on a futures contract for a stock index that is not closed out is based on the difference between the futures price when the initial position was created and the futures price at

A) the settlement date.
B) the date at which the futures price reaches its maximum.
C) the date at which the futures price reaches its minimum.
D) the date three months beyond the date when the initial position was taken.