The operation of selling hedging is mainly applicable to the following situations: (1) Holding a certain commodity or asset (holding a spot long position at this time) and worrying about the decrease of market value or sales revenue of the commodity or asset held by it. (2) Buying commodities or assets settled in futures at a fixed price (holding spot long positions at this time), fearing that the market price will fall, thus reducing the market value or sales income of commodities or assets. (3) It is expected that a certain commodity or asset will be sold in the future, but the sales price has not yet been determined. I'm worried that the falling market price will reduce its sales revenue. Item b belongs to the first case.