Answer:
Hello. You did not put the answer options, but one of the biggest innovations that allowed the planting of crops in mountainous regions was a technique called terracing.
Step-by-step explanation:
Terracing is the technique that allows the division of sloping areas in mountainous regions. This technique, although ancient, was an innovation in the American continent, which allowed planting in the mountainous region, since it was possible to establish irrigation systems without causing soil erosion or the drainage of nutrients. In addition, the terracing increases the cultivation areas and can even retain rainwater, reducing irrigation costs.