Question

Topsoil contains which of the following?
(a) Humus and living organisms only.
(b) Humus and soil particles only.
(c) Humus, living organisms, and plants.
(d) Humus, living organisms, and soil particles.

Answer 1

Hint: Soil formation is influenced by mainly five classic factors, they are- parent material, climate, topography, organisms, and time. The areas that receive more rainfall will have more developed soil than the areas that receive lower rainfall.

Complete solution
Soil helps not only in the vegetation but also helps in the the pedosphere, where various interactions between climate occur (including water, air, temperature), soil life (micro-organisms, plants, animals) and its residues, the mineral material of the first and added rock and its position within the landscape. During its formation, the profile slowly deepens and develops characteristic layers, called 'horizons', while a gentle state balance is approached. The topmost layer of the soil horizon is found to be dark brownish in color due to the presence of a large amount of humus in it which is made up by the decomposition of the dead and decaying organic matter with the help of soil living bacteria sling with some soil particles. This layer is found to be around 2 to 8 inches deep inside.
Soil users (such as agronomists) earlier showed very little interest in the dynamics of soil. They saw soil as a medium whose chemical, physical, and biological properties were useful for the services of agronomic productivity. On the other hand, the agronomic applications of the soil characteristics (edaphic properties) didn't specialize by the pedologists and geologists but upon its reference to the character and history of landscapes. Today, there's an integration of the 2 disciplinary approaches as a part of the landscape and environmental sciences.

So, the correct answer is ‘Humus, living organisms, and soil particles’.

Note:
Pedology is considered as the science that studies the genesis, nature, distribution, and use of the potentiality of soil resources. Pedology is a study of the soil that focuses mainly on understanding the formation of soil, evolution, and therefore the theoretical frameworks through which we understand a soil body(s), often within the context of the natural environment.