Which of the following was a cause of northern european immigration to the united states in the 1840s and 1850s?

The two main groups to immigrate during this time were the Irish and British. The Irish bitterly resented the British who ruled Ireland. Many rented from British landlords who treated them as second class sub-citizens. It was densely populated, and suffered from intense economic hardship. Aside from political persecution, the Irish economy depended heavily on the potato crop which was wiped out by potato blight. 

Does this help?