Which organization is responsible for regulating the practice of architecture in the Philippines?

The Professional Regulatory Board of Architecture is the correct answer because it is the designated authority in the Philippines responsible for the regulation and licensing of architects. This board operates under the Professional Regulation Commission (PRC) and is tasked with ensuring that the practice of architecture follows legal and ethical standards established by national laws.

The board's responsibilities include the formulation of rules and regulations related to the profession, overseeing the conduct of licensure examinations, and enforcing compliance with professional standards. This governance ensures that architects are qualified and adhere to the required competencies in their work, protecting both the profession and the public interest.

In contrast, the other organizations mentioned do not possess regulatory power. The Department of Architecture does not exist as a formal government body within the context of professional regulation, while the Philippine Institute of Architects and the National Association of Architects are professional organizations that support the profession but do not have the authority to regulate or license architects in the same way that the Professional Regulatory Board does. Thus, the Professional Regulatory Board of Architecture plays a crucial role in maintaining the integrity and standards of architectural practice in the Philippines.