Step 1: Analyze the climate of the Great Plains of India (Indo-Gangetic Plain).
This region experiences hot summers, cool winters, and a strong monsoon season where most of the rainfall occurs. Winters are generally dry.
Step 2: Decode the Köppen climate classification codes. - A: Tropical climates. Af = Tropical rainforest, Am = Tropical monsoon. - B: Dry (arid and semi-arid) climates. BS = Semi-arid (steppe). - C: Temperate climates. w = dry winter, g = Ganges type (hottest month before the summer monsoon). - Cwg: A temperate climate with dry winters and a hot, Ganges-type summer.
Step 3: Match the climate to the code. The description of a temperate climate with hot summers and a distinct dry season (winter) perfectly matches the Cwg classification. This is the code assigned to the majority of the Indo-Gangetic Plain.