Look at the map of europe. which of these areas practiced christianity in 600 ce?

The correct answer is D) Jerusalem.

The area that practiced Christianity in 600 CE was Jerusalem.

People practiced Christianity in Jerusalem at that time, but in a matter of years, it expanded to new territories throughout the Roman Empire.  

At the beginning of Christianity, it was spread by the disciples of Jesus and by Paul of Tarsus who was converted by a vision of Christ. From there, he became a promoter of Christianity. By the third century C.E., Christianity was the dominant religion in the Mediterranean region. After that, the Roman Empire expanded to the north and west of the continent, spreading the doctrine all across Europe.

genetics is the study of how dna works, the methodologies defining the new recent technologies allow scientist to have a panoramic view of the entire dna landscape, especially how genomes interact with their environment, including off course, factors outside their organisms.

thus is very possible the existence of both scenarios, where populations of isolated individuals have different genetic traits, and share traits related to genetic mutation, due rats can easily travel overseas using human transport channels. so scientists could get a vast number of data, including human interaction, evolution of rodents, health development, spread of infections, development of new organisms, how genomes evolve in different environments and so on.