The correct answer is (d). Dhanbad is the most densely inhabited district of Chhotanagpur plateau because of all the factors mentioned in the options.
(a) Fertile soil and irrigational facilities by canals from the Damodar: The Damodar River is a major river in eastern India. It flows through the states of Jharkhand, West Bengal, and Odisha. The Damodar Valley Corporation (DVC) is a government-owned corporation that was established in 1948 to develop the Damodar Valley for irrigation, flood control, and power generation. The DVC has constructed a number of dams and canals on the Damodar River, which have provided irrigation facilities to a large area of land in Jharkhand and West Bengal. The fertile soil of this region is suitable for growing a variety of crops, including rice, wheat, sugarcane, and jute.
(b) Availability of coal iron ore, mica, copper etc.: Dhanbad is located in the heart of the Jharkhand coalfields. The coalfields of Jharkhand are the largest in India and account for about 25% of the country’s coal production. The coalfields are also rich in iron ore, mica, copper, and other minerals. The availability of these minerals has led to the development of mining industries in Dhanbad.
(c) Development of mining industries and industrialization: Dhanbad is a major industrial city in Jharkhand. The city is home to a number of coal mines, iron and steel plants, and other industries. The development of these industries has led to the growth of population in Dhanbad.
In conclusion, Dhanbad is the most densely inhabited district of Chhotanagpur plateau because of all the factors mentioned in the options.