The correct option is (c) 1 and 3 only.
Explanation
The distribution of population is heavily influenced by geographical factors such as topography, climate, soil fertility, and availability of water. In the Ganga-Brahmaputra basin, the contrast between the mountainous terrain and the plains creates distinct settlement patterns.Statement 1 is Correct: The environment plays a dominant role in the distribution of the population. Factors like steep slopes, harsh climate, and fertile soil determine where people settle. Consequently, the population is unevenly distributed across the basin based on these environmental conditions.
Statement 2 is Incorrect: The mountain areas of the basin (e.g., the Himalayas) have steep slopes, rugged terrain, and often harsh climatic conditions, which make them inhospitable for large-scale settlement. Therefore, the population density in the mountain areas is low, not high.
Statement 3 is Correct: The plain areas provide the most suitable land for human habitation. The soil is fertile (alluvial soil), the terrain is flat, and water is abundant, making it ideal for agriculture and infrastructure development. As a result, the density of population in the plains is very high.
Key Takeaway: Topography is a primary determinant of population density; fertile plains support dense populations due to agricultural suitability, while rugged mountain terrains support sparse populations.