When a scientist is conducting research about all the plants and wildlife in the mojave desert as well as the desert’s resources, such as water and soil, the scientist is studying
a. a community.
b. a population.
c. a species.
d. an ecosystem.

The correct answer is- D. an ecosystem.

An ecosystem can be described as system of biological community ( including all life forms such as plants and animals) that interact among themselves as well as with the non living components ( such as air, water , soil, temperature) present in their environment.

Thus, In the question, scientist who is conducting research about all the plants and wildlife in the Mojave Desert as well as the desert’s resources, such as water and soil, the scientist is studying an ecosystem.

Thus, option D) is the right answer.

The correct answer is d)ecosystem.

A ecosystem is community of both biotic(living) and abiotic (non-living) components such as air, water, and soil so if a scientist is conducting research on wildlife as well as on water and soil than he/she is studying a ecosystem.

estuaries are the partially enclosed coastal bodies of brackish water formed at the mouth of sea where river meets an ocean. it is a transition zone between river and sea water so estuaries are influenced to both marine environment such as tides, waves and to riverine such as flow of fresh water and sediments. the mixing of sea and fresh water provide high level of nutrients, making estuaries a high product habitats.

many estuaries suffers degradation from a variety of human activities like erosion from deforestation, overgrazing, overfishing, drainage and eutrophication.

so from the above statement answers will be

1. false as estuaries are formed due to both brackish and freshwater.

2.true, due to high productivity estuaries are breeding ground for many marine species.

3. direct and indirect activities of man that contribute to pollution and deposition of sediments.

they have identical fossils of organisms that have evolved over time.

both have animal fossils preserved in them due to weathering and erosion.

they contain different fossils because life on earth has changed through time.

the fossils in them were formed on the surface of earth due to exposure to sunlight.