Well one push factor would be they wanted to escape religious and political prosecution. Another is the Potato Famine. This was when their potatoes were contaminated and many died from starvation and disease.
I hope this helps somehow ;)
Answer:
b or d but i mostly think its b
Explanation:
I am pretty sure the answer is B) sedimentation but i could be wrong. i haven't don't this subject in a year. lol