NCERT Solutions for Class 9th Social Science Chapter 1 Why Should We Study Social Science? — In-text Questions

Because the chapter's answer is that they are outcomes, not accidents. Page 11 states it directly: Social Science explains these variations "as outcomes of geographical, historical, cultural, and economic factors".

• Geographical. India contains mountains, deserts, plateaus, river plains and a long coastline. What people can grow, build with, eat and wear differs accordingly, and the terrain itself once limited how much neighbouring communities mixed.
• Historical. Different regions were settled at different times, ruled by different dynasties, reached by different trade routes and touched by different waves of migration. Each of those encounters left something behind in the language and the customs.
• Cultural. Communities developed their own languages, literatures, festivals, crafts, music and forms of worship — and these were valued and preserved, not treated as things to be given up.
• Economic. Occupation shapes a way of life. A fishing community, a pastoral community, a weaving town and a rice-growing village will differ in their calendars, their skills and their food, because their work differs.

Because they are passed on. The very first page of the chapter names "the traditions and ideas passed down through generations" as one of the forces that shape our lives.

• Learning at home and in the community. Mother tongue, food, dress, songs, festivals and craft skills are learnt in childhood, before school ever begins, and are taught in turn to the next generation.
• Institutions that carry them. Families, places of worship, village and caste associations, schools, local theatre and music traditions, and craft guilds all preserve a practice and give it occasions to be performed.
• Written and remembered forms. Texts, manuscripts, oral traditions and folklore hold a tradition steady across centuries. The chapter's itihāsa-purāṇa tradition is precisely this — through stories it "reinforces enduring ideals and values, offering a sense of identity and purpose".
• The work people do. As long as a region continues to fish, herd or weave, the calendar, vocabulary and festivals built around that work continue with it.
• Identity. People value their language and customs as their own, so they choose to maintain them — and often maintain them most carefully when living far from home.