The foothills of Arunachal Pradesh have soils that are:

The correct answer is: a) Rich in organic matter.

The foothills of Arunachal Pradesh are covered in dense forests, which means that there is a lot of organic matter in the soil. Organic matter is important for soil health because it helps to improve drainage, water retention, and nutrient availability. It also helps to suppress weeds and pests.

The other options are incorrect because:

• Option b) is incorrect because the foothills of Arunachal Pradesh are not highly acidic.
• Option c) is incorrect because the foothills of Arunachal Pradesh are not sandy and infertile.
• Option d) is incorrect because the foothills of Arunachal Pradesh are not alkaline in nature.