Which one of the following is the characteristic climate of the Tropical Savannah Region?

The answer is D. The tropical savanna climate (Aw in Köppen's scheme) lies on the poleward margins of the equatorial belt. Its defining feature is a definite alternation of a wet season and a dry season, with rain falling mainly when the sun is overhead, that is, in the summer half of the year.

Why the others fail:

• A describes the equatorial type (Af), where the ITCZ stays over the region and rain falls in almost every month. Savanna has no such continuity.
• B is the Mediterranean pattern (Csa/Csb), where winter brings the rain and summers are dry. Savanna rain comes in summer, not winter.
• C is wrong because the dry season in savanna is long, often six to eight months in the Sudan and Sahel belts. A short dry season would push the climate towards equatorial.

Core concept: seasonality of rainfall driven by the shifting ITCZ and monsoon circulation. The same logic explains the tall grass and scattered trees of the savanna, and it links to Mains GS-I questions on climate and ecology in Africa and South America (Llanos, Cerrado).

Trap: aspirants pick A or B from vague memory of "rain everywhere" or "winter rain" without placing the region relative to the ITCZ.