Basel Convention - Biodiversity Conservation
The Basel Convention is an international treaty that aims to reduce and control the movements of hazardous wastes between countries. It was adopted in 1989 and came into force in 1992. The primary objective of the Basel Convention is to protect human health and the environment from the adverse effects of hazardous wastes.

Kyoto Protocol - Climate Change
The Kyoto Protocol is an international agreement that was adopted in 1997 and came into force in 2005. It is an extension of the United Nations Framework Convention on Climate Change (UNFCCC) and sets binding targets for the reduction of greenhouse gas emissions. The main goal of the Kyoto Protocol is to combat climate change by reducing the emissions of six greenhouse gases, namely carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride.

Montreal Protocol - Global Warming
The Montreal Protocol is an international treaty that was adopted in 1987 and entered into force in 1989. It is designed to protect the ozone layer by phasing out the production and consumption of substances that deplete it, such as chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). The depletion of the ozone layer has indirect effects on global warming, as it allows more ultraviolet radiation to reach the Earth's surface, contributing to the greenhouse effect.

Ramsar Convention - Groundwater Pollution
The Ramsar Convention is an international treaty that was adopted in 1971 and came into force in 1975. It is named after the city of Ramsar in Iran, where the convention was signed. The Ramsar Convention's primary objective is the conservation and wise use of wetlands, which include areas such as marshes, peatlands, lakes, and rivers. While wetlands play a crucial role in maintaining water quality, they are not specifically focused on addressing groundwater pollution.

In conclusion, the correctly matched pair is:

b) Kyoto Protocol - Climate Change