Arrange the sentences in the correct order to form a coherent paragraph. A. Climate change is one of the biggest challenges facing the world today. B. It causes rising temperatures, melting glaciers, and unpredictable weather patterns. C. These changes threaten ecosystems and human societies globally. D. Therefore, urgent action is needed to reduce its impact.

1. BACD
2. ABCD
3. DABC
4. ACBD