Suppose that you sell CDT short at $23 and at the same time you write a call option on CDT with a strike price of $15 and a premium of $2.
What is the combined profit or loss on the two positions together if just prior to expiration of the call option the price of CDT is $21?
Assume that you cover your short position (meaning you get rid of the short position) just prior to the time of option expiration.