Concept:
The United Nations has played an important role in maintaining international peace and security.
To strengthen peacekeeping and conflict resolution mechanisms, several important reports and policies have been introduced by UN Secretaries-General.
Step 1: Understand the meaning of 'Agenda for Peace'.
'Agenda for Peace' was a major UN report focusing on:
• Preventive diplomacy
• Peacemaking
• Peacekeeping
• Post-conflict peace-building
The report aimed to improve the UN's ability to manage international conflicts after the Cold War.
Step 2: Identify the UN Secretary-General associated with the report.
The report:
\[
\textit{Agenda for Peace}
\]
was presented in:
\[
1992
\]
by:
\[
\text{Boutros Boutros-Ghali}
\]
who served as the Secretary-General of the United Nations.
Step 3: Understand the significance of the report.
The report emphasized:
• Peaceful settlement of disputes
• International cooperation
• Expansion of UN peacekeeping operations
• Strengthening global security systems
Step 4: Eliminate incorrect options.
• Trygve Lie -- First UN Secretary-General
• U Thant -- Earlier UN Secretary-General
• Boutros Boutros-Ghali -- Correct
• Ban Ki-moon -- Served much later
Step 5: Conclusion.
Hence, the correct answer is:
\[
\boxed{\text{Boutros Boutros-Ghali}}
\]