Final answer:
The three Köppen climate designations ideal for growing potatoes in the Andean region are the Tundra climate (ET), Subtropical Highland climate (Cwb), and Humid Subtropical climate (Cfa) due to their respective conditions which are exploited for specialized agriculture.
Step-by-step explanation:
Using the Köppen climate classification system, the three specific designations in the Andean region that create an ideal environment for growing potatoes include Tundra climate (ET), characterized by cold conditions suitable for cold-resistant crops; Subtropical Highland climate (Cwb), which offers cooler temperatures and moderate rainfall, making it suitable for potato varieties adapted to such conditions; and the Humid Subtropical climate (Cfa), though less common, it can provide a suitable environment for certain potato varieties at lower Andean elevations.
The Andean region's varied elevations create microclimates which are exploited for agriculture, with Peruvian potato farmers having knowledge of numerous potato varieties and matching them to specific environmental conditions to ensure a healthy harvest. This expertise and environmental diversity are reasons for the vast number of potato types cultivated in this area.