the third Choice is the answer i think.
Answer;
both positive and negative
Explanation;
-The elephant are keystone species, playing an important role in maintaining the biodiversity of the ecosystems in which they live. They may have both negative and positive interactions to the environment. For example, during the dry season, elephants use their tusks to dig for water, which has a positive impact to the surrounding.
-They clear large amounts of vegetation, which removes habitats for some organisms but makes the area inviting for other organisms. This has both positive and negative impact to the ecosystem.
The environment is studied at different levels & stages.
Biosphere: The biosphere is the zone in which life exists. It consists of the atmosphere& the hydrosphere alongwith the earth surface where living beings live.
The biome is a community of plants and animals (flaura & fauna).
Community: A community is a group of people/living beings who live in a specific location. It is used to describe two or more populations of different species that exist at same place.
Population: A population is the multiple individuals or living organisms of a single species that live in an area.
The populations are formed by lalrge number of groups of organisms.
Group of populations form communities. The group of all communities form a biome, which exist in the biosphere.
The diagram shows:
It helps the cell by making sure everything gets circulated throughout the cell
A. Releasing a stimulus when hormones increase or decrease I think