(1) When the market exchange rate is lower than 1.64, the importer is willing not to perform the contract, because if the contract is performed, it will cost 160000 US dollars to buy 160000 pounds, plus the option fee of 4000 US dollars paid in advance, which is1640000.

② When the market exchange rate is equal to 1.64, the importer's performance and non-performance are the same. According to the option contract, the cost of purchasing 654.38+million pounds in the spot market is164,000 USD.

③ When the market exchange rate is higher than 1.64, the importer should perform the contract, because the cost of performing the contract is only 164000 USD, which is lower than the cost of buying sterling cash in the foreign exchange market.

Therefore, when the importer buys eight options contracts, the total cost converted into 654.38+10,000 pounds after three months will definitely not exceed1640,000 dollars, thus achieving the purpose of preventing foreign exchange risks.

Exporters use foreign exchange options to trade contracts to prevent foreign exchange risks in the same way as importers.