According to Thornthwaite's scheme, what type of climate does eastern Bihar have?

Explanation

According to Thornthwaite’s scheme, the climate of Eastern Bihar is mainly of the C2 type. However, due to variations in the distribution of rainfall within the region, both dry sub-humid (C1) and moist sub-humid (C2) sub-types are found. The northern and north-eastern districts of Eastern Bihar (Purnia, Araria, Kishanganj, etc.) fall under the C2 category because of higher rainfall, whereas the south-western part (Bhagalpur, etc.) comes under the C1 category due to comparatively lower rainfall. The Bihar Public Service Commission has considered option (a) as the correct answer in its answer key.