The correct answer is: D) All of the above
Opencast mining is a surface mining technique in which minerals and ores are extracted from the earth by removing the overlying soil and rock. It is the most common method of mining coal, iron ore, and limestone.
Opencast mining is a relatively inexpensive and efficient method of mining, but it can have a significant environmental impact. The removal of the overlying soil and rock can expose groundwater to contamination, and the mining process can generate large amounts of dust and noise.
In recent years, there has been a growing trend towards the use of underground mining techniques, which are less environmentally disruptive. However, opencast mining is still the most common method of mining for many minerals and ores.
Here is a brief description of each option:
- Coal is a fossil fuel that is formed from the remains of ancient plants. It is used to generate electricity, produce steel, and make other products.
- Limestone is a sedimentary rock that is composed of calcium carbonate. It is used to make cement, lime, and other products.
- Iron is a metal that is used to make steel. It is extracted from iron ore, which is a rock that contains iron.
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