Option 4: Generational knowledge passed down by artisans -> The passage explicitly states that "Each region in India has its own distinct craft, passed down through generations of artisans" and emphasizes that artisans "continue to keep these traditions alive for generations to come." This generational transmission of knowledge and skills is identified as the key factor in preservation. The other options (government support, modern technologies, and international demand) are not mentioned anywhere in the passage. -> correct