D. Why people like other people.
That's social, not geographic.
Answer:
Iron and Bronze Age.
Explanation:
According to the widely accepted Kurgan hypothesis or Steppe theory, the Indo-European language and culture spread in several stages from the Proto-Indo-European Urheimat in the Eurasian Pontic steppes into Western Europe, Central and South Asia, through folk migrations and so-called elite recruitment. The 1st millennium BC was the period of time between from the year 1000 BC to 1 BC.
Pacific
Mid-West
South
Atlantic
Ice caps and glaciers is your answer.
