The answers are A. The introduction of a new variety of seeds helped the growth of potatoes.
Because the Spanish conquistadors found the potato when they arrived in Peru, mainly looking for gold. They failed to find gold but they also realized that potatoes were also a treasure.
And C. Potatoes improved the European diet nutritionally.
It began with recommendations from the Royal Society to cultivate potatoes, and then became popular during food shortages. With time, the European diet expanded and began to include potatoes in it because of the high nutritional value of the vegetable helped mitigate diseases like scurvy, tuberculosis and measles.