Final answer:
Filomena's act of withdrawing her offer to sell rare books to Rhonda before acceptance is an example of a revocation of an offer. This is permissible in contract law as long as the revocation is communicated to the offeree before any acceptance occurs.
Step-by-step explanation:
When Filomena offers to sell Rhonda her collection of rare books and then revokes the offer before Rhonda can accept, this is an example of a revocation of an offer. In contract law, an offer can be withdrawn by the offeror at any time before it is accepted by the offeree, provided that the revocation is communicated to the offeree. Since Filomena communicated her change of mind to Rhonda before Rhonda accepted, the act constitutes a revocation. If Rhonda had accepted the offer before Filomena had a chance to revoke it, there would have been a legally binding agreement. Since the withdrawal happened before acceptance, no such agreement was formed.
Answer: c) Revocation of an offer