Studio or office of a resident medical or osteopathic physician, dentist, chiropodist, podiatrist, physiotherapist, chiropractor, lawyer, engineer, architect, landscape architect, accountant, insurance agent or real estate agent, provided that:
(a) Such use shall be located within the dwelling and shall be clearly incidental to the primary residential use.
(b) Not more than one additional person shall be employed on said premises as an assistant to the professional occupant.
(c) Such use shall not include the confinement of any person under care or treatment.