Gravel in the soil helps crops grow better, since they provide nutrients. Sand however, doesn't impact the crops growth at all.
<u>Explanation:</u>
For example, considering the international hardwood agreements which took effect in the year 2006, we observe included in the agreements are some policies intended to encourage the sustainable management of tropical rainforest.
While selective logging on the other hand also encourages sustainable management of tropical rainforests. For example, trees are selectively cut down so as to still allow a healthy forest ecosystem. Also, continuous replanting occurs every time a tree is cut down.
Answer:
<em>The correct option is theories. </em>
Explanation:
A scientific theory is a detailed explanation of natural researches which are supported through evidence. Scientific theories can be changed if other evidence are made which support another theory. Hence, scientific theories can change. The concepts of plate tectonics and evolution change overtime whenever new pieces of evidence are discovered. Hence, they are scientific theories.
Other options such as hypotheses are not correct because a hypothesis is just a tentative statement which can either be proved to be correct or wrong. Observations are not made on evidences hence the option observations is also not correct.
