The correct answer is Clouds. Explanation & Key Takeaways: • Clouds • Clouds help regulate Earth's temperature. • They bring rain to different regions. • Clouds develop out of the process of changing moisture from a gas to liquid through a process called convection. • There are three forms of clouds • Cirrus: curly or fibrous • Stratus: sheets or layers • Cumulus: Heaped or piled Related Concepts: • Soil • Soils are a complex mixture of water, air, minerals, and a number of organisms that are decaying. • It forms at the surface of the land. • It is the skin of the earth. • It is capable of supporting plant life and is vital to life on earth. • It is classified into four types: • Sandy Soil • Silt Soil • Clay Soil • Loamy Soil • Mountains • It is an elevated portion of the Earth's crust generally with steep sides. • Forces inside and outside the earth manage the shape of the earth's surface. • There are four types of mountains: • Volcanic Mountains • F old Mountains • Block Mountain • Residual Mountains