The pair of districts having Red and Yellow Soils is –

Concept

Soils are classified by parent material, climate, and the region that produces them. In Rajasthan, red and yellow soils form on the older crystalline and metamorphic rocks of the southern and south-eastern hilly tracts, where moderate weathering and iron oxidation give the soil its red-to-yellow colour.

Where red and yellow soils occur

Standard Rajasthan-geography references place the red and yellow soil belt in the southern/south-eastern districts:

• Sirohi

• Ajmer

• Bhilwara

• Sawai Madhopur (and, in broader lists, Udaipur, Chittorgarh and Tonk)

Applying it to the options

Of the pairs offered, Ajmer and Sirohi both fall inside this red-and-yellow soil belt, so the pair Ajmer – Sirohi is the one that matches the soil type asked about.

Cross-check (why the other regions differ)

• Kota and Bundi lie on the Hadoti plateau, whose characteristic soil is medium (black) soil formed on Deccan-trap-type basaltic material, not red and yellow soil.

• Alwar and Bharatpur, in the eastern plains, are dominated by alluvial and loamy soils.

• Pali and Jodhpur, towards the western arid zone, carry sandy desert (arid) soils.

Hence the pair of districts having red and yellow soils is Ajmer – Sirohi.