Explanation
A put option is a contract that gives the buyer the right, but not the obligation, to sell a set number of shares of an underlying asset at a set price within a specified time frame. The buyer of a put option expects the price of the underlying asset to fall below the strike price before the expiration date. Therefore, A is the correct answer.
References: Put Option: What It Is, How It Works, and How to Trade Them, Put: What It Is and How It Works in Investing, With Examples, Put Options: Definition, Overview, and Example