D) The Earth has changed over geologic time. Hope it helps!
Explanation:
Primary succession is one of two types of biological and ecological succession of plant life, occurring in an environment in which new substrate devoid of vegetation and other organisms usually lacking soil, such as a lava flow or area left from retreated glacier, is deposited.[1] In other words, it is the gradual growth of an ecosystem over a longer period of time.[2][3]
Primary succession occurring over time. The soil depths increase with respect to the increase in decomposition of organic matter. and there is a gradual increase of species diversity in the ecosystem. The labels I-VII represent the different stages of primary succession. I-bare rocks, II-pioneers (mosses, lichen, algae, fungi), III-annual herbaceous plants, IV-perennial herbaceous plants and grasses, V-shrubs, VI-shade intolerant trees, VII-shade tolerant trees.
Primary succession on Rangitoto Island
In contrast, secondary succession occurs on substrate that previously supported vegetation before an ecological disturbance from smaller things like floods, hurricanes, tornadoes, and fires which destroyed the plant life.[4]
The answer is Mutualism because they are both benefiting
Potable water is water that is safe to drink
Answer:
The correct answer is case control study.
Explanation:
A study in which a comparison is made between the patients carrying the disease with the patients not carrying the disease is known as the case-control study. In the mentioned study, the one carrying the disease is termed as cases, and the one that does not possess the disease is termed as controls.
This form of study is generally done to predict the association between the disease and the risk factor. In case-control studies, only observation is done as no attempt is made to change the course of the condition. The prime objective of the study is to predict the exposure of the risk elements for the individuals present in two groups, that is, controls and cases. This form of study is also called case-referent studies or retrospective studies.
