Correct option is D
The traveler who described the two-tiered postal system of the Delhi Sultanate (the horse-post called ulug and the foot-post called dawa) was Ibn Battuta.
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Ibn Battuta, a famous Moroccan traveler, visited India during the reign of Sultan Muhammad bin Tughlaq (14th century). His work, Rihla (Travels), provides a detailed and valuable account of the Sultanate administration.
Horse-Post (Ulug): This rapid service was used primarily for delivering official royal mail, intelligence reports, and transporting fruits and goods for the Sultan. Ulug refers to the swift horse relays.
Foot-Post (Dawa): This pedestrian service, which was even faster than the horse-post for local communication, had three stations per mile. Dawa means a running post.