Which field of anthropology studies the hunting and gathering techniques of early man?

The correct answer is Archeology. The other subcategories of Anthropology as the study about humans are Cultural Anthropology, Biological Anthropology and Linguistic Anthropology.  

The study of human activity which includes biofacts, artifacts and cultural activities like early hunting, is a branch of humanities and also regarded as a social science, is Archaeology and especially Prehistoric Archaeology, which stretches back to ancient eras of human existence through the exploration of remains.

Explanation:

the historians cited in the article all agree with one another about the cause of the civil war. despite coming from different backgrounds and cultures, the historians agree that slavery was the root cause of the civil war. the fact that all these historiansgenerally agree with one another makes their shared viewpoints more reliable and valid, especially because the historians have different backgrounds and all work for the well-respected institutions of howard university, clemson university, and the university of colorado.

i honestly speaking this is too long