Correct Option
Statement (d) is not correct. Mountain areas, primarily the Himalayas and associated ranges, account for approximately 16% of India's total geographical area. The statement that mountain areas cover about thirty percent of the surface area is an overestimation. India's major physiographic divisions and their approximate area coverage are:
- Northern Mountains: Approximately 16%
- Indo-Gangetic Plain: Approximately 23%
- Peninsular Plateau: Approximately 44%
- Coastal Plains and Islands: Remaining portion
Incorrect Options
Statement (a) is correct. About one-third of India's geographical area records more than 750 millimetres of annual rainfall. Regions such as the Western Ghats, the Northeastern states, and parts of Eastern and Central India receive substantial rainfall, contributing to this statistic.
Statement (b) is correct. Wells, including tube-wells, constitute the dominant source of irrigation in India. They account for over 60% of the total irrigated area, surpassing other sources like canals and tanks in terms of coverage.
Statement (c) is correct. Alluvial soil is the predominant soil type found in the northern plains of India. These plains, formed by the depositional activity of the Indus, Ganga, Brahmaputra, and their tributaries, are characterized by fertile alluvial soils covering states like Punjab, Haryana, Uttar Pradesh, Bihar, and West Bengal.