A population is A. all plant species that exist in a single region at a single time. B. all individuals of a single species that exist together in a given region. C. the sum of all individuals of a species that live in different ecosystems. D. all similar animal species that live in the same ecosystem.

B

Explanation:

a population in the ecosystem can  be defined as all the individual of a species that exist together at a given place and time.

the historians cited in the article all agree with one another about the cause of the civil war. despite coming from different backgrounds and cultures, the historians agree that slavery was the root cause of the civil war. the fact that all these historiansgenerally agree with one another makes their shared viewpoints more reliable and valid, especially because the historians have different backgrounds and all work for the well-respected institutions of howard university, clemson university, and the university of colorado.

president reagan was a good presidant and should be presidant if he was still alive

explanation: