History · Espionage and Postal System in Delhi Sultanate

Regarding the espionage and postal systems during the Delhi Sultanate, consider the following statements: 1. Balban is credited with establishing a highly efficient network of spies (barids) to strengthen central political control. 2. Ibn Battuta describes a dual postal system under Muhammad bin Tughlaq: the horse-post (uluq) and the foot-post (dawa), noting that the foot-post was extremely rapid. 3. The Barid-i-Mumalik functioned mainly as a provincial revenue supervisor rather than heading intelligence, while the Munhiyans were formally appointed court officers responsible for official record-keeping. 4. Alauddin Khalji used the spy system so effectively that, according to Barani, nobles avoided speaking freely even inside their homes. Which of the statements given above are correct?