The breaking up and decay of exposed rocks by temperature changes, frost action, plants, animals and human activity is called:

weathering

The correct answer is Option (3) - weathering

Weathering is the process by which rocks and minerals are broken down into smaller fragments or altered in composition due to various environmental factors. It is a natural phenomenon that occurs over time and plays a fundamental role in shaping the Earth's surface. Weathering can occur through several mechanisms, including physical, chemical, and biological processes:

1. Physical Weathering: Physical weathering, also known as mechanical weathering, involves the physical breakdown of rocks into smaller fragments without changing their chemical composition. This process is primarily driven by physical forces such as temperature changes, frost action, pressure release, and abrasion. For example, repeated freezing and thawing of water within cracks in rocks can exert pressure, causing the rocks to fragment into smaller pieces.
2. Chemical Weathering: Chemical weathering involves the alteration of rock minerals through chemical reactions with water, oxygen, acids, and other substances present in the environment. Chemical weathering processes include hydration, oxidation, dissolution, and hydrolysis, which lead to the breakdown of minerals and the formation of new minerals or mineral by-products. For example, the reaction of carbon dioxide with water in the atmosphere produces carbonic acid, which can dissolve minerals such as calcite in limestone rocks.
3. Biological Weathering: Biological weathering involves the role of living organisms in breaking down rocks and minerals. Plant roots can penetrate cracks in rocks, exerting pressure and causing mechanical weathering. Similarly, burrowing animals, such as earthworms and rodents, can fragment rocks through their activities. Furthermore, the secretion of organic acids by plants and microorganisms can contribute to chemical weathering processes.
4. Human Activity: Human activities, such as mining, construction, agriculture, and urbanization, can also accelerate the weathering of rocks and minerals. Mining activities expose rocks to weathering processes by removing vegetation and protective layers of soil. Construction activities may alter drainage patterns and increase the exposure of rocks to weathering agents. Agricultural practices can lead to soil erosion, which exposes underlying rocks to weathering. Additionally, the emission of pollutants from industrial sources can contribute to chemical weathering processes.

Overall, weathering is a complex and continuous process that acts on rocks and minerals at the Earth's surface, leading to their decomposition, fragmentation, and alteration. It plays a critical role in soil formation, landscape evolution, and the cycling of Earth's materials.