The ordinance of the legislative body declaring a need for a commission to function in the community may declare a need that the commission function only with respect to a redevelopment agency or that the commission function with respect to a redevelopment agency and a housing authority. If the ordinance declares a need that the commission function only with respect to a redevelopment agency, then the commission shall not have the powers, duties, and responsibilities of a housing authority and the provisions requiring that two of the commissioners be tenants of the housing authority shall be inapplicable.