You have entered into a short straddle position with strike prices, Xc and Xp, very close to the current spot rate, St. For this option combination to be profitable:

a. Spot rates up to the expiration cannot diverge much from the current spot rate
b. Spot rates up to the expiration must diverge substantially from the current spot rate
c. Spot rates up to the expiration must decrease substantially but not increase
d. Spot rates up to the expiration must increase substantially but not decrease