About 95% of Earth's crust is made up of igneous rocks.

Igneous rocks are one of the three main types of rocks found on Earth, along with sedimentary and metamorphic rocks. They are formed from the solidification of molten material called magma or lava. When magma cools and solidifies beneath the Earth's surface, it forms intrusive igneous rocks. When lava erupts onto the surface and cools rapidly, it forms extrusive igneous rocks.

Here are some key points to explain why igneous rocks make up about 95% of Earth's crust:

1. Igneous rocks are formed from the cooling and solidification of molten material. Magma is generated in the Earth's mantle through processes like partial melting and rises to the surface through volcanic activity. As a result, igneous rocks are abundant in the Earth's crust.

2. Extrusive igneous rocks are formed from lava that cools quickly on the Earth's surface. These rocks include basalt, andesite, and rhyolite. They are commonly found in volcanic areas and cover large portions of the ocean floor. Basalt, in particular, is the most common type of extrusive igneous rock and makes up a significant portion of the Earth's crust.

3. Intrusive igneous rocks are formed when magma cools slowly beneath the Earth's surface. These rocks include granite, gabbro, and diorite. Granite, with its coarse-grained texture, is a common example of an intrusive igneous rock. It is widely distributed in continental crust and makes up a significant portion of the Earth's crust.

4. The Earth's crust is composed of various types of rocks, but igneous rocks are the most abundant. This is because the Earth's crust has been subjected to extensive volcanic activity throughout its history. As a result, the accumulation of extrusive and intrusive igneous rocks over millions of years has led to their dominance in the crust.

In conclusion, about 95% of Earth's crust is made up of igneous rocks. Their formation from magma or lava and their abundance in both intrusive and extrusive forms contribute to their significant presence in the Earth's crust.

Option A