Answer:
Invalid, because under the UCC the acceptance must mirror the offer
Explanation:
§ 2-207 of the Uniform Commercial Code (UCC) enforces the mirror image rule. The mirror image rules states that in order for a valid contract to be formed, the offeree (Office Supply) must accept all the terms included in the offer (by Blue Cross) and cannot modify or add any terms. Any term that changes the original offer results in no contract.