The correct option is 1 and 3 only.
Explanation
The United Nations Conference on Environment and Development (UNCED), also known as the "Earth Summit," was a landmark global conference held to reconcile worldwide economic development with the protection of the environment.
Statement 1 is Correct. The Earth Summit was held in Rio de Janeiro, Brazil, from June 3 to 14, 1992. It was characterized by massive global participation, involving 172 governments (with 108 heads of state), approximately 2,400 representatives from non-governmental organizations (NGOs), and various corporate entities and media personnel.
Statement 2 is Incorrect. The summit did not focus on trade tariffs; rather, it addressed urgent problems of environmental protection and socio-economic development. Far from ignoring biodiversity, one of the major achievements of the summit was the opening of the Convention on Biological Diversity (CBD) for signature. It also addressed climate change (via the UNFCCC) and forest management.
Statement 3 is Correct. One of the primary documents adopted at the summit was Agenda 21. This is a comprehensive, non-binding blueprint for action to be taken globally, nationally, and locally by organizations of the UN system, governments, and major groups in every area in which humans impact the environment.
Key Takeaway: The major outcomes of the 1992 Rio Earth Summit include the Rio Declaration on Environment and Development, Agenda 21, the Forest Principles, and the opening for signature of legally binding conventions: the UNFCCC and the CBD.