Dobos was admitted to a hospital with a serious condition that required around- the- clock nursing care. The hospital, on orders from Dobos’s doctor, requested Nursing Care Services, Inc. to care for Dobos while she was in the hospital and for a two- week period while she was at home. When Nursing Care Services sent a bill, Dobos claimed she was not liable because she had not signed a written contract or personally made an oral agreement for their services, although she was well aware of what her doctor had requested and had readily accepted the care provided. Under what theory can Nursing Care Services collect?