Stock Options, Once Granted, Allow an Executive to Buy Stock

Stock options, once granted, allow an executive to buy stock

A) in future years at a fixed discount rate depending on performance.
B) in future years with a guaranteed return.
C) at a price equivalent to the company's book value.
D) in future years at a price determined when the stock option was issued.
E) whenever they would like to do so at a price negotiated with the company board of directors.