Which of the Following Is the Best Definition of Put

Which of the following is the best definition of put option?

A) A plot showing the gains and losses that will occur on a contract as the result of unexpected price changes.
B) An option that gives the owner the right, but not the obligation, to sell an asset.
C) A plot showing how the value of the firm is affected by changes in prices or rates.
D) An agreement by two parties to exchange, or swap, specified cash flows at specified intervals in the future.
E) Short-run financial risk arising from the need to buy or sell at uncertain prices or rates in the near future.