________ are longitudinal valleys formed as a result of folding when Eurasian plates and Indian plates collided.

Correct option is D

The correct answer is (d) Duns.

Duns are longitudinal valleys formed due to the folding of the earth's crust during the collision of the Eurasian plate and the Indian plate. This geological process, known as orogeny, led to the formation of these valleys, which are found mainly in the Himalayan foothills.
Example: The Dehradun and Kangra Dun are famous examples of such valleys.

Additional Information:

• Ridges: Elevated areas of land formed by tectonic forces but not valleys.
• Ranges: Mountain ranges formed by the collision of tectonic plates, not valleys.
• Craters: Circular depressions formed by volcanic activity, not tectonic folding.

Duns are specific features of the Himalayan foothills and are significant in terms of geographical and hydrological characteristics.