The correct answer is option 'A': Crust.

Explanation:

The Earth is made up of several layers, including the crust, mantle, and core. Minerals are primarily extracted from the crust, which is the outermost layer of the Earth.

1. The Earth's Crust:
- The crust is the thin, solid outermost layer of the Earth.
- It is composed of a variety of rocks, minerals, and sediments.
- The crust is divided into two main types: continental crust and oceanic crust.
- Continental crust is thicker and less dense compared to oceanic crust, which is thinner and denser.

2. Mineral Extraction:
- Minerals are naturally occurring inorganic substances with a definite chemical composition and crystal structure.
- They are found in various forms in the Earth's crust and are extracted for various purposes, including industrial, economic, and scientific uses.
- Mining is the process of extracting minerals from the Earth's crust.
- Different methods, such as open-pit mining, underground mining, and placer mining, are used depending on the type and location of the mineral deposit.

3. Mineral Resources in the Crust:
- The Earth's crust contains a wide range of mineral resources, including metals (such as gold, copper, iron, and aluminum), gemstones (such as diamonds and rubies), industrial minerals (such as limestone, gypsum, and silica), and fossil fuels (such as coal, oil, and natural gas).
- These minerals are distributed unevenly across the Earth's crust and can be found in various geological formations, such as veins, ore bodies, and sedimentary deposits.

4. Importance of Mineral Extraction:
- Mineral extraction plays a crucial role in various industries and sectors of the economy.
- Metals are used in construction, manufacturing, electronics, transportation, and energy production.
- Industrial minerals are essential for building materials, chemicals, ceramics, and agriculture.
- Gemstones have both aesthetic and economic value.
- Fossil fuels are the primary source of energy for heat, electricity, and transportation.

In conclusion, minerals are primarily extracted from the Earth's crust, which is the outermost layer. The crust contains a wide range of mineral resources that are vital for various industries and sectors. Mining is the process used to extract these minerals from the Earth's crust.