The correct option is 2 and 3 only.
Explanation
Population distribution refers to the way people are spaced over the earth's surface. This distribution is highly uneven and is primarily influenced by geographical factors such as topography, climate, soil fertility, and availability of water, as well as economic and social factors.
Statement-wise Analysis:
- Statement 1 is Incorrect. River valleys are historically and currently the most densely populated areas of the world, not sparsely populated. They provide fresh water, fertile soils suitable for intensive agriculture, and flat terrain which facilitates the construction of roads, railways, and industries. Examples include the Nile Valley, the Yangtze, and the Ganga plains. While flooding is a risk, the economic and survival benefits attract dense settlements.
- Statement 2 is Correct. Rugged terrain, such as mountainous and hilly areas, presents significant challenges for human settlement. These areas hinder the development of transport and communication networks. Furthermore, the lack of flat land makes agricultural mechanization and industrial development difficult. Consequently, regions like the Himalayas or the Andes tend to be sparsely populated.
- Statement 3 is Correct. The Ganga plains are characterized by fertile alluvial soil, a favorable climate, and abundant water availability. These factors support intensive agriculture and industrial activities, making the region one of the most densely populated areas in the world.
Key Takeaway:
Geographical factors play a decisive role in population distribution; flat, fertile river valleys attract high population densities due to agricultural and infrastructural viability, whereas rugged mountainous terrains deter settlement due to accessibility and developmental constraints.