Geographically, which is the largest agroclimatic zone of Rajasthan?

Correct option is B

Rajasthan is divided into several agroclimatic zones based on climate, soil, rainfall, and topography. Among these, the Hyper Arid Partial Irrigated Western Zone is the largest geographically, covering vast desert areas primarily in the western part of the state such as Barmer, Jaisalmer, and Bikaner.
This zone is characterized by extreme aridity, limited rainfall, and sparse vegetation. Agriculture here is heavily dependent on irrigation sources like canals and tube wells.
(a) Arid western plain: Though extensive, it is smaller than the hyper-arid zone and receives slightly more rainfall.
(b) Hyper arid partial irrigated western zone: Correct. It is the largest in area among all agroclimatic zones in Rajasthan.
(c) Sub humid southern plain: Located in the southern region with relatively better rainfall but smaller in area.
(d) Humid south eastern plain: High rainfall but limited to a smaller geographic area.