The correct answer is option 3: Spanish. The potato was indeed introduced to Europe by the Spanish. During the 16th century, Spanish explorers brought potatoes back from their expeditions in South America and introduced them to Europe. The potatoes quickly gained popularity as a food source due to their versatility and ability to grow in a variety of climates. From Spain, the cultivation of potatoes spread to other European countries. It is important to note that while options 1, 2, and 4 may have played a role in spreading the popularity of potatoes in Europe, it was the Spanish who were responsible for initially introducing the crop to the continent.