What Happens When an Offeree Accepts the Offer by an Offeror

What happens when an offeree accepts the offer by an offeror?

A) Each party is legally bound if the other elements of the contract have been satisfied.
B) There is conditional agreement which is based on the parties' goodwill towards each other.
C) Full agreement has not been reached.The parties are not legally bound until they sign a written agreement that contains all the relevant terms they have been negotiating.
D) There is a valid offer in response to an invitation to treat.Agreement has not yet been reached.