Let’s match the international agreements with the corresponding issues:
P. Ramsar Convention: The Ramsar Convention deals with the conservation of wetlands, so P matches with (iv) Conservation of wetlands.
Q. Kyoto Protocol: The Kyoto Protocol is an international treaty that targets climate change by reducing greenhouse gas emissions, so Q matches with (iii) Climate change.
R. Basel Convention: The Basel Convention focuses on the trans-boundary movement of hazardous wastes, so R matches with (ii) Trans-boundary movement of hazardous wastes.
S. Montreal Protocol: The Montreal Protocol aims to protect the ozone layer by phasing out substances that deplete it, so S matches with (i) Ozone depletion.
Thus, the correct matching is P-(iv), Q-(iii), R-(ii), S-(i).
Final Answer:
\[
\boxed{\text{(A) P-(iv), Q-(iii), R-(ii), S-(i)}}.
\]