The correct option is C Shershah
Sher Shah Suri built the Purana Qila at Delhi. Purana Qila is a fort situated on the Delhi Mathura Road. It was constructed on the historical site of Indraprastha by Sher Shah Suri. Sher Shah strengthened the citadel of Dinpanah and renamed it as Shergarh. The wall of Purana Qila are some 0.33 meters in thickness and are terminated at each corner by massive bastions.