Gina contracted with Countrywide Lawn & Garden for some landscaping work on her estate. After Countrywide had finished its work, Gina complained that it did not comply with the contract. She sent Countrywide a check for 90% of the contract amount along with a letter stating that by cashing this check, Countrywide accepted this amount as full payment of her obligation under the contract. Countrywide deposited the check and then sued Gina for breach of contract. Gina could respond: