The correct answer is D. All of these.
Kangra, Shimla, Mandi, and Bilaspur are all districts in the Indian state of Himachal Pradesh. These districts are suffering from soil acidity problem. Soil acidity is a condition in which the pH of the soil is below 7. This can cause a number of problems for plants, including stunted growth, chlorosis, and death.
There are a number of factors that can contribute to soil acidity, including the presence of acidic rocks, the use of acidic fertilizers, and the leaching of minerals from the soil. Soil acidity can also be caused by natural processes, such as the decomposition of organic matter.
There are a number of ways to manage soil acidity, including the use of lime, gypsum, and other amendments. These amendments can help to neutralize the acidity in the soil and make it more suitable for plant growth.
It is important to manage soil acidity in order to ensure the health of plants and the productivity of agricultural land.