What do you call the process of cultural traits spreading from one culture to another?

cultural diffusion

Explanation:

Cultural Diffusion. The spread of culture traits from one region to another is called cultural diffusion.

i would go with the last one

the catholic church withhold people's access to the bible during the middle ages.

people could go to church and listen to the teachings, but it was absolutely forbidden to own and/or read the books of both the old and new testaments. it was also prohibited to translate the books (which where originally in biblical hebrew) to any other language.

this was done so the church could remain in control of what their teachings were and to enhance their importance and power, while also being able to judge people's actions through information that was unavailable for the general public.