Answer:
The correct answer is C. Because of a potato famine in the 1840s, hundreds of thousands of Irish people came to the United States.
Step-by-step explanation:
The Great Famine was a period of starvation, disease and mass emigration in Ireland between 1845 and 1849, caused by a plague that affected potato harvests in Europe. Approximately two fifths of the Irish population depended exclusively on the potato for subsistence. During the famine, around one million people died and a million more emigrated from Ireland (mostly to the United States), causing the population of the island to fall by 20% and 25%.