Match Column-I with Column-II :

Column-I		Column-II

(a) Kyoto Protocol

(1) 2009

(b) Copenhagen Summit

(2) 1972

(c) Montreal Protocol

(3) 1997

(d) Stockholm Conference

(4) 1987

Codes :
(a) (b) (c) (d)

Correct option is B

The correct answer is (b).

Introduction

This question maps pivotal milestones in international environmental diplomacy to their respective years of adoption.

These conferences and protocols form the bedrock of global environmental governance, addressing everything from ozone depletion to anthropogenic climate change.

Information Booster

Kyoto Protocol (A -> 3): Adopted in 1997, it operationalized the UNFCCC by committing industrialized countries to limit and reduce greenhouse gas emissions.
Copenhagen Summit (B -> 1): Held in 2009 (COP 15), it famously struggled to create a binding post-Kyoto framework but succeeded in drafting the Copenhagen Accord.
Montreal Protocol (C -> 4): Finalized in 1987, this highly successful treaty phased out the production of numerous substances responsible for ozone depletion (CFCs, Halons).
Stockholm Conference (D -> 2): Officially the UN Conference on the Human Environment held in 1972, it is widely regarded as the historical genesis of the modern international environmental movement.
The Stockholm Conference led directly to the creation of the United Nations Environment Programme (UNEP).
Understanding this chronological evolution is essential for grasping how international policy shifted from general declarations (Stockholm) to specific, binding targets (Montreal/Kyoto).

Additional Knowledge

The Earth Summit (UNCED) in Rio de Janeiro, another massive historical milestone not listed here, took place in 1992, birthing the UNFCCC, CBD, and UNCCD.
The Paris Agreement, the modern successor to the Kyoto Protocol, was adopted subsequently in 2015 at COP 21.
The Vienna Convention, which provided the framework for the Montreal Protocol, was adopted in 1985.