Answer:
C. ethnogenesis.
Step-by-step explanation:
Ethnogenesis is a term that describes the creation and development of ethnic groups, often associated with common identity, and it can occur as a result of self identification or outside identification. Hence, they become ethnically distinct from the various and surrounding groups.
Therefore in this case, the Tutsi people and Hutu farmers, start seeing themselves differently, which made them to form and develop different ethnic group that are distinct from each other. And, this is a phenomenon known as ethnogenesis