When Can an Offeror Who Has Promised to Keep the Offer

When can an offeror who has promised to keep the offer open to a specific date, be able to validly withdraw their offer before that date?

A) The offeror gives a reasonable explanation for his decision to withdraw the offer
B) At any time so long as the other party had not paid for an option to keep it open
C) They would not be allowed to just withdraw the offer
D) The offeror does not intend to make a new offer concerning the same subject matter to any other person for a greater consideration
E) They can only withdraw it if a reasonable time has passed or a set date was set to revoke the offer