A US firm has an account payable of $200,000 YEN in 90 days, and it believes firmly in the forecasts that the japanese yen will further appreciate during the next three months. The most common stragety to eliminate or cover the potential risk of loss on the firm's yen obligation is to

a. sell yen 90 days later at the spot rate

b. sell a 90 day yen forward contract

c. buy yen spot now

d. buy a 90 day yen forward contract

e. buy yen 90 days later at the spot rate