The correct option, including statements 1, 2, and 4, reflects fundamental differences between permaculture and conventional chemical farming practices. Permaculture emphasizes biodiversity and ecological balance, avoiding monoculture to foster resilience and enhance soil health (statement 1). Conversely, conventional farming often leads to increased soil salinity due to heavy reliance on chemical fertilizers and irrigation practices, which can disrupt natural soil ecosystems (statement 2). Additionally, mulching is a critical strategy in permaculture to improve soil moisture retention and support a diverse range of crops, whereas conventional farming does not prioritize such techniques, focusing instead on chemical inputs and monocultural crops (statement 4). Understanding these differences is essential for recognizing sustainable agricultural practices in the context of environmental and ecological studies relevant to the UPSC curriculum.