The correct option is (c).
Explanation
The distribution of the global population is highly uneven, primarily influenced by geographical factors such as topography, climate, soil fertility, and water availability.
- Statement 1 is Correct: It is a standard geographical fact that approximately 90 per cent of the world’s population occupies only about 30 per cent of the land area. The remaining 70 per cent of the land surface is either sparsely populated or uninhabited due to harsh environmental conditions.
- Statement 2 is Incorrect: Areas characterized by steep slopes, rugged topography, and high altitudes are generally sparsely populated. These regions present significant challenges for agricultural activities, the construction of infrastructure (roads, housing), and industrial development.
- Statement 3 is Correct: Plains and river valleys are typically the most densely populated areas globally. These regions offer flat land and fertile soils, which are highly suitable for agriculture and facilitate the development of settlements and transport networks (e.g., the Indo-Gangetic plains).
Key Takeaway: Population density is directly correlated with the carrying capacity of the land; fertile plains and river valleys support high densities, while rugged terrain and extreme climates limit human settlement.