Option d is the correct answer. Firuz Shah Tughlaq established the Public Works Department in the Delhi Sultanate, focusing on infrastructure development through canal, well, and road construction. His efforts aimed to improve public welfare, earning him the title 'Sultan of Constructions'. The department managed vital projects like roads, bridges, and canals. To attract skilled workers, Firuz Shah offered competitive wages and benefits, ensuring the success of these extensive endeavors for enhancing public facilities and transportation.