Answer:
B) Keith's prior act of dealing and conduct with Harry confirms acceptance of the offer.
Step-by-step explanation:
The UCC establishes several rules regarding valid offers, but when both parties are merchants, the rules are much more flexible since both parties are generally involve in this type of transactions because they are part of their work.
For example, an offer between merchants doesn't need to be sent out every time in writing and accepted with a signature (as offers over $500 between non-merchants), the previous deals, requests and offers can serve as confirmation of acceptance.
In this case, Harry's previous acceptance of Keith's shipments during one year serve as a confirmation of acceptance of a current offer. Harry knew that Keith was going to deliver the goods next month, and if he didn't want them anymore, he should have clearly stated it.