Final answer:
Historians should emphasize both agriculture and human sacrifice when studying ancient civilizations, as both had significant impacts on society and reflect the complexity of their economic, religious, and political dimensions.
Step-by-step explanation:
When examining the cultural shift in the Mississippian tradition, agriculture and human sacrifice both had significant impacts on their society. The adoption of maize agriculture was a major reason for this cultural shift (option a.), as it led to a greater division of labor, increased specialization, and the emergence of a priestly class that derived authority by interpreting the supernatural. This led to the construction of elaborate monuments and the performance of rituals that were religiously significant. In contrast, human sacrifice was a public display of power (option b.), designed to instill terror and demonstrate the might of empires like the Maya and Aztecs. The question at hand asks whether historians should emphasize agriculture, human sacrifice, neither, or both when studying ancient civilizations.
By prioritizing both aspects, a more nuanced history is presented. Therefore, option d. Emphasize both agriculture and human sacrifice can be considered the most balanced choice. Agriculture resulted in a stable food supply, economic surplus, and social stratification, which influenced the complexity of societies. Human sacrifice, on the other hand, reflects the spiritual beliefs, political structures, and the intensity of power displays in ceremonies. Effective historical analysis needs to address the interplay between economic, religious, and political dimensions in shaping civilizations.