Which of the following soils is the most suitable for the cultivation of cotton in India?
A. Red soil
B. Laterite soil
C. Alluvial soil
D. Regur Soil

Hint: Cotton plants are susceptible to the aluminum concentration often found in soils with a pH below that level.
Cotton plants prefer to do well in deep, well-drained and highly fertile sandy loam soils with a pH of between 5.5 and 7.5, cotton plants prefer to do well.
It is sown from March-May and with the onset of the monsoon, the rain fed crop is in June-July.

Complete answer:
Red soil: Red soil is a type of soil that grows under deciduous or mixed forest in a humid, temperate, moist environment, with thin organic and organic-mineral layers overlaying a leached yellowish-brown layer lying on a red illuvium layer. Generally, red soil is derived from crystalline rock. Maize, rice, beans, millets, tobacco, oilseeds, potatoes, and fruits are grown in red soil.
Laterite soil: Laterite, a surface layer rich in iron oxide derived from a wide spectrum of rock weathering conditions that are heavily oxidizing and leaching. In tropical and subtropical areas where the atmosphere is hot, it develops. Laterites are suitable for the production of plantations such as tea, coffee, rubber, cinchona, coconut.
Alluvial soil: Soils that are formed by surface water are alluvial soils. Along rivers, in floodplains and deltas, stream terraces, and places called alluvial fans. Maize, wheat, sugarcane, cotton, jute, potato and vegetables are grown in alluvial soil.
Regur soil: Regur soil is also known as black soil is ideal for growing cotton and is known as black cotton soil. They are rich in soil nutrients, such as calcium carbonate, magnesium, potash and lime. These soils are generally poor in phosphoric contents.

Hence, Option (D) is the correct answer.

Note: Black soils are deficient in nitrogen, organic matter and phosphorus.
The soils are typically abundant in the clay mineral group of montmorillonite and beidellitic.
Cotton is a Kharif crop. It is found in Rajasthan, Uttar Pradesh, Punjab, Haryana, Madhya Pradesh, Gujarat, Maharashtra and portions of Andhra Pradesh & Karnataka