Match the following and choose the correct option:
i. A - horizon a. Small lumps of rocks
ii. B - horizon b. Hard layer which is difficult to dig
iii. C - horizon c. Dark in colour and rich in humus
iv. Bedrock d. Less humus and more minerals, compact
i - c; ii - d; iii - a; iv - b
Horizon A is the topmost layer of soil. It is dark in colour due to the presence of a large amount of humus. It makes the soil nutrient rich and fertile. The layer is soft, porous and can retain more water.
Horizon B is the layer below horizon A and has less quantity of humus but at the same time, it contains more minerals.
Horizon C is the third layer which is composed of partially eroded small lumps of rocks.
Bedrock is the layer below horizon C and is very hard and difficult to dig through.