Exercising the Option Can Best Be Defined As

Exercising the option can best be defined as:

A) The act of buying or selling the underlying asset via the option contract.
B) The fixed price in the option contract at which the holder can buy or sell the underlying asset. Also the exercise price or strike price.
C) The last day on which an option can be exercised.
D) The change in the stock price divided by the change in the call price.
E) A feature included in the terms of a new issue of debt or preferred shares to make the issue more attractive to initial investors.