Explanation: The cities of Delhi, Islamabad, and Dhaka share a common geographical feature that has historically supported their dense populations: their proximity to major rivers. This relationship between urban development and river systems is a fundamental concept in geography and urban planning.
Delhi, the capital of India, is located near the Yamuna River, which is a tributary of the Ganges. The Yamuna River has been a crucial source of water for the city, providing drinking water, irrigation for agriculture, and a means of transportation. The river has also played a significant role in the city's economic development, facilitating trade and commerce.
Islamabad, the capital of Pakistan, is situated near the Ravi River, which is another tributary of the Indus River. The Ravi River has been essential for the city's water supply and agricultural activities. It also serves as a natural boundary and a means of transportation, contributing to the city's growth and development.
Dhaka, the capital of Bangladesh, is located near the Buriganga River, which is a distributary of the Ganges-Brahmaputra delta. The Buriganga River is vital for the city's water supply, industrial activities, and transportation. It has been a key factor in the city's rapid urbanization and economic growth.
The presence of these rivers near the cities has provided several advantages that have supported their dense populations:
1. **Water Supply**: Rivers provide a reliable source of water for drinking, cooking, and sanitation, which is essential for the health and well-being of the population.
2. **Agriculture**: Rivers support irrigation, which is crucial for agriculture, ensuring food security and supporting the livelihoods of the population.
3. **Transportation**: Rivers serve as natural waterways, facilitating the movement of goods and people, which is essential for economic activities and trade.
4. **Economic Development**: Rivers have historically been centers of economic activity, supporting industries, markets, and trade, which contribute to the growth and development of the cities.
In contrast, the other options do not directly support the dense populations of these cities:
- **Coastal Location**: While coastal cities can benefit from maritime trade and fishing, the cities in question are not located on the coast.
- **Location South of the Tropic of Cancer**: This geographical feature does not provide the necessary resources for urban development.
- **Location Near the Himalaya Mountains**: The Himalayas are not near these cities, and while mountains can influence climate and water resources, they are not the primary factor supporting the dense populations of these cities.
In conclusion, the proximity to major rivers is a key factor that has historically supported the dense populations of Delhi, Islamabad, and Dhaka. Understanding this relationship between urban development and river systems is crucial for comprehending the geographical and economic factors that influence the growth and sustainability of cities.