Adoption of clean clearing of land in the tropical rain forest is not advisable because it

The statement is saying that adopting clean clearing of land in the tropical rainforest is not advisable and the question is asking for the reason why. The answer is option A, which states that it encourages erosion and leaching. This is because clean clearing involves the removal of all vegetation, including roots and debris, which leaves the soil exposed to erosion by wind and water. The organic matter that would have been left behind to decay and provide nutrients to the soil is also removed, which leads to leaching of nutrients. Therefore, clean clearing is not recommended as it has negative effects on the soil and the environment in general.