Hey there!
Just imagine if you were in (America), and there were other cultures popping out of no where and started being in your country. For sure, there would be alot of confusion, am I right?
It's same in this case, the result's in cultural diffusion would be
groups of people dominate their religion or language over others.
The Incorrect answer would be (b) and also (c) and (d). They really do not make any sense in this regard.
Your correct answer would be . . .

Hope this helps.
~Jurgen