Section 2. No acquisition, rehabilitation, demolition, or other improvement which shall involve the displacement of occupants of dwelling units or business units shall be made unless and until the bureau has qualified a relocation advisory agency to give relocation assistance to the occupants to be displaced. Any agency, public or private, may be qualified by the bureau to act as a relocation agency until such time as the bureau may, on stated grounds, withdraw qualifications; or the bureau may qualify any agency, public or private, proposed by a displacing agency to act as a relocation agency with respect to particular acquisitions. The bureau may qualify a displacing agency to act as the relocation agency with respect to particular acquisitions.