Answer:
2. Two civilizations along the same river have very similar religious beliefs and marriage customs.
Step-by-step explanation:
In sociology, the term cultural diffusion refers to the process that happens when the beliefs and social traditions of one culture are transmitted to another one and they end up sharing beliefs or traditions. Therefore, cultural diffusion is about similarities, not about differences.
If we take a look at our options we see that options 1 and 4 talk about differences between two cultures so these options are wrong.
Option 3 mentions that SOMETIMES two cultures hunt the same animals for food, however, hunting is not a belief or a tradition.
Finally, option 2 mentions two different civilizations that share religious beliefs and marriage customs. Since we are talking about similarities, this is most likely the result of cultural diffusion.