The word in italics is "millennia." Based on the context clues in the sentence, "for many millennia," we can determine that "millennia" refers to a long period of time, specifically thousands of years. Therefore, the best answer that matches the word in italics is "thousands of years."
Based on the context provided, the word in italics is "millennia." To determine its meaning, we can use the surrounding words and phrases. In this case, the clue is "thousands of years." Millennia refers to a period of one thousand years. Therefore, the best answer that matches the word in italics is "thousands of years."
