The correct answer is option 'A', which states that the UNCCD is the sole legally binding international agreement linking environment and development to sustainable land management. Let's dive into the details to understand why this answer is correct.

Introduction to UNCCD:
The UNCCD stands for the United Nations Convention to Combat Desertification. It is a global framework that aims to address the issues of desertification, land degradation, and drought. This convention was adopted in 1994 and has been ratified by 197 countries, making it one of the most widely supported international agreements.

Linking Environment and Development:
The UNCCD recognizes the interlinkages between environment and development. It acknowledges that sustainable land management is essential for achieving sustainable development goals, including poverty eradication, food security, and environmental sustainability. By promoting sustainable land management practices, the UNCCD aims to ensure the long-term productivity and resilience of ecosystems, thereby supporting both environmental and socio-economic objectives.

Key Objectives of UNCCD:
The UNCCD has several key objectives, which are closely aligned with the link between environment and development:

1. Combating Desertification: The convention aims to prevent and combat desertification, land degradation, and drought by promoting sustainable land management practices.

2. Enhancing Sustainable Development: The UNCCD recognizes that sustainable land management is crucial for achieving sustainable development. It promotes the integration of environmental and developmental considerations in land use planning and decision-making processes.

3. Promoting Participation and Cooperation: The convention emphasizes the importance of involving all stakeholders, including local communities, in the design and implementation of sustainable land management strategies. It encourages international cooperation and exchange of knowledge and best practices.

4. Mobilizing Financial and Technical Support: The UNCCD aims to mobilize resources to support developing countries in implementing sustainable land management practices. It promotes financial and technical assistance, capacity-building, and technology transfer to enhance the resilience of ecosystems and communities.

Conclusion:
In conclusion, the UNCCD is the sole legally binding international agreement that links environment and development to sustainable land management. It recognizes the importance of sustainable land management for achieving sustainable development goals and addresses the issues of desertification, land degradation, and drought. By promoting participation, cooperation, and financial support, the UNCCD aims to combat desertification and enhance the resilience of ecosystems and communities worldwide.