In the early 1800s, potatoes became the main food staple for the people of Ireland. In 1845, a fungus native to South America, Phytophthora infestans, began to infect potato plants, causing potato blight and making the tubers inedible. Over the next several years, most of the potato plants in the country were destroyed by this invasive species. Which of the following statements correctly explains why the Irish potato famine occurred?

A) The arrival of ships from South America led to human introduction of the disease.
B) A drought across Ireland in 1844 led to more damaged potato plants that were susceptible to infection.
C) An increase in trade with other European countries led to the introduction of plants that were already infected with the fungus.
D) Ireland’s climate became closer to that of South America, which allowed the fungus to infect potato plants and reproduce.