The correct answer is option-2: Soil.

Inceptisols, Entisols, Vertisols, and Mollisols are all orders of soil. Soil is a mixture of minerals, organic matter, gases, liquids, and organisms that together support plant growth. These different orders of soil are categorized based on their properties, formation processes, and location.

- Inceptisols are relatively young soils that have a weakly developed or no soil horizon. They typically form in areas with regular additions of mineral material, such as floodplains or steep slopes.

- Entisols are also young soils that have minimal development of horizons. They often occur in areas with little time for soil formation, such as sand dunes or volcanic deposits.

- Vertisols are soils characterized by high clay content that undergo substantial shrinkage and swelling with changes in moisture. This property makes them prone to cracking and self-mixing, creating a unique soil structure.

- Mollisols are soils that have a dark, fertile surface horizon rich in organic matter. They are typically found in regions with grassland vegetation and have excellent agricultural productivity.

Understanding the different orders of soil is important because it helps us comprehend the soil properties, fertility, and their suitability for various land