7. What is the layer of Earth that contains all known living creatures?
Answer: B
The layer of Earth that contains all known living creatures is the crust.
The crust is the outermost layer of the Earth and is where all known living organisms exist. It provides the necessary conditions for life, including access to water, air, and nutrients.
A) Inner core
The inner core is the Earth's innermost layer, composed mainly of solid iron and nickel. It is extremely hot and under immense pressure, making it inhospitable to any form of life.
B) Crust
The crust is indeed the layer of Earth that contains all known living creatures. It is the thin, solid outer shell that supports ecosystems, providing habitats for plants, animals, and humans.
C) Outer core
The outer core is a liquid layer composed primarily of iron and nickel located beneath the mantle and above the inner core. Its extreme temperatures and fluid nature make it unsuitable for supporting life.
D) Mantle
The mantle is the layer between the crust and the outer core, composed of semi-solid rock that flows slowly over geological time. Although it plays a crucial role in tectonic activity, it does not host any living organisms.
Conclusion
The crust is the only layer of the Earth that supports all known life due to its surface composition and conditions favorable for living organisms. The inner core, outer core, and mantle do not provide the necessary environments for life, making them unsuitable compared to the crust.