For the purpose of this article, any person shall be deemed to be in business or engaging in nonprofit enterprise, and thus subject to the requirements of this article, when he does one act of:
(a) Selling any goods or service;
(b) Soliciting business or offering goods or services for sale or hire;
(c) Acquiring or using any vehicle or any premises in the City for business purposes.
(1978 Code Sec.14-4.)