Answer: BCD

Analysis of futures spread refers to the price difference between two futures contracts in different months or varieties in the futures market. Different from speculative trading, in spread trading, traders are concerned about whether the spread between related futures contracts is within a reasonable range. If the price difference is unreasonable, traders can use this unreasonable price difference to trade related futures contracts in the opposite direction, and then close the two contracts at the same time to gain income when the price difference tends to be reasonable. Item A belongs to spot arbitrage.