Answer: Option A
:
A, B, and C
The addition of harmful or toxic chemicals to the soil which renders it unproductive is called soil pollution. 
Causes:
1. The use of synthetic toxic chemicals such as pesticides, insecticides, fertilizers, which are used on plants, alters the nature of the soil and gradually decrease its productivity.
2. Industrial activities generate different kinds of wastes. Some of them are highly toxic in nature. The by-products are contaminated and are emitted into the land bodies nearby.
3. Waste materials are disposed of by the means of the landfill, which harmfully affects the fertility of the soil.
4. Acid rain, which is caused by air pollution, deposits acids in the soil through water runoffs. The acids are particularly harmful to the soil.