What was the most common reason why a large number of irish immigrants came to the united states in the 1840s?
they were looking for jobs as skilled laborers.
they wanted to escape a potato famine.
they wanted to live in less crowded conditions.
they were trying to escape oppression.

The correct answer is "They wanted to escape a potato famine". Ireland suffered from a large famine crisis from 1845 to 1849 called the "Great Famine" or the "Irish Potato Famine". This happened mostly by the late blight disease that destroys both the leaves and the edible roots of the potatoes. A large number of Irish people came to the United States in that period looking for a escape from the famine.

b) the confederacy had to pay all union war expenses.