Anthropologist asserts that many of the early Native Americans who lived on the Plains did not engage in planting crops but to hunt, living primarily on buffalo meat. Here which of the underlying word is incorrect?

Here the word 'primarily' is incorrect because without 'primarily' word the sentence is appropriate. If add the word 'primarily' it refers the other line is exist in next. But the other line is not exist. So, the Ans is D.