The correct answer is: A) Heat and sun.
Laterite soils are formed in tropical and subtropical regions with high rainfall and intense sunlight. The high temperatures and rainfall cause the soil to leach out its soluble minerals, leaving behind a layer of iron and aluminum oxides. This layer is hard and impermeable, and it can become even harder when exposed to heat and sun.
Excessive rain can also cause laterite soils to harden, but this is usually not as severe as the effects of heat and sun. Frost and snow do not have a significant impact on laterite soils. Animal grazing can also cause laterite soils to harden, but this is usually only a problem if the grazing is excessive.
Here is a more detailed explanation of each option:
- Option A: Heat and sun. Laterite soils are formed in tropical and subtropical regions with high rainfall and intense sunlight. The high temperatures and rainfall cause the soil to leach out its soluble minerals, leaving behind a layer of iron and aluminum oxides. This layer is hard and impermeable, and it can become even harder when exposed to heat and sun.
- Option B: Excessive rain. Excessive rain can also cause laterite soils to harden, but this is usually not as severe as the effects of heat and sun. The rain can cause the soil to become compacted, which makes it harder to work with. It can also cause the soil to erode, which can lead to the loss of topsoil.
- Option C: Frost and snow. Frost and snow do not have a significant impact on laterite soils. The cold temperatures do not cause the soil to harden, and the snow does not cause the soil to erode.
- Option D: Animal grazing. Animal grazing can also cause laterite soils to harden, but this is usually only a problem if the grazing is excessive. The animals can trample the soil, which makes it harder to work with. They can also eat the plants that help to hold the soil in place, which can lead to erosion.