Hello There! ^_^
Your question: What were the three main Indian groups before European explorers arrived..?
Your answer: The Mayan, the Aztecs and the Incas were the three main Indian groups before European explorers arrived.
Hope this helps!
Answer: The El Nino Southern Oscillation, a periodic warming and cooling of the surface waters of the central and eastern equatorial Pacific Ocean, is an ongoing cycle of long duration. That is, as far back as weather records go, there is evidence of this seasonal variation.
Explanation:
It’s the outer core, it’s mainly made of metal
A. Belgium, France, and Germany
Hope this helps! :))