They became merchants, carpenters, teachers, clergy, and (most often) farmers. Their landscape was Watonwan County in western Minnesota. Young families worked hard to build a life. They came from a farming tradition that included methods unknown to many Americans. As usual, new ideas were viewed with some doubt. The use of crop rotation, for example, was common for the newcomers. They also used potassium for fertilizer. Their practices produced better crops than other farms. A good idea is hard to ignore, and they soon gained status as first-rate farmers. Which best paraphrases this paragraph?

Immigrant families worked extremely hard when they came to America and quickly gained status.
Using potassium as fertilizer, a technique of immigrant farmers, helped many people.
New farming techniques had a major impact on farming in the Midwest, producing first-rate crops.
Immigrant families brought new farming techniques to America, which proved very effective.