When was the IRR of PD 1570 signed?

The correct response is anchored in identifying the essential details of Presidential Decree No. 1570, which pertains to the rules and regulations addressing various aspects of the energy sector in the Philippines. The IRR (Implementing Rules and Regulations) of PD 1570 was signed on September 23, 1982. This decree was significant as it set the groundwork for policies related to the exploration and development of natural resources, highlighting the government's strategic approach to managing energy resources in the country.

The date is critical for understanding the timeline of energy policy development in the Philippines and indicates the government's priority in establishing regulatory frameworks during that period. The other choices reflect different years or dates that do not align with the actual signing of the IRR, which is foundational for comprehending the legal and regulatory landscape during that era in the Philippines’ energy sector.