i) An offer may be written or oral.
ii) General advertisements, price lists and general inquiries are not offers.
iii) To be effective, an offer must be communicated by the offeror (person making the offer) to the offeree (recipient of the offer).
(You must keep these two terms clear at all times. The questions may try to “trick” you by providing a potential answer that is false for one of the parties and true for the other.)
iv) An offer can be rejected by the offeree. It can also be revoked by the offeror as long as it was not already accepted. Logically, the offeror must communicate a revocation to the offeree.