Answer:
As per Kristy Johnson's letter where she mentioned the clauses of the acceptance of offer, she clearly mentioned that she will consider a response only if it is in written form and is sent through US mail.
Now Judy did as per the clauses and sent her a written acceptance through US mail whereas Michael telephoned her and let her know of her acceptance. If Kristy is adamant on her terms that she clearly mentioned in her letter to both and will stick to her word, then technically, it is Judy's fair right on the Montana interests whereas Michaels telephone call will be discarded as it did not fulfill the terms.