Cherokee Rose Design & Build LLC ("Cherokee") hired Mullenburg Inc. to install underground utilities in a subdivision. After the work was done, Mullenburg sued Cherokee, alleging that it had not been paid. Cherokee's lawyer sent a proposed settlement to Mullenburg. It stated that Cherokee would sell three lots to Mullenburg for $75,000; both parties would fully release each other; Mullenburg would dismiss the lawsuit; and that each party would bear its own costs. Mullenburg's lawyer responded, writing, "My client has authorized me to convey its acceptance of the settlement offer," but Cherokee would have to "convey marketable title by way of a warranty deed," and Mullenburg would like Cherokee to provide a title insurance commitment. After Cherokee's lawyer prepared releases, Mullenburg realized it had to pay $75,000 for the lots and alleged it had not made an unconditional acceptance because of the requirement of marketable title and the request for a title insurance commitment. Was Mullenburg's response an acceptance or a counteroffer? Please explain the impact of each.