Taking the exact same position in the underlying asset as in the futures contract is not a valid method for terminating a position in a futures contract. This is because having a long position in the futures contract and simultaneously having a long position in the underlying asset will double the risk and exposure in that particular asset. This does not terminate the futures contract but rather increases the risk associated with it. Therefore, this method is not a valid way to terminate a futures contract.

Choice A is incorrect. Delivering the underlying assets/goods of a futures contract is indeed a valid method for terminating a position in a futures contract. This process involves the physical delivery of the commodity or asset that underlies the futures contract, which effectively closes out the position.

Choice B is incorrect. Cash-settling in which futures are marked to market - based on the settlement price of the last trading day, is also an acceptable method for terminating a position in a futures contract. In this case, no physical delivery takes place; instead, cash changes hands based on the difference between the future's purchase price and its final settlement price.

Choice C is incorrect. The investor can indeed take an opposite position to his current one as another way to terminate his existing position in a futures contract. This process involves entering into another futures contract with identical terms but opposite positions (long if currently short and vice versa), effectively neutralizing or closing out their original position.