Step 1: Understanding Bakhtiyar Khalji.
Bakhtiyar Khalji was a military commander who is best known for his conquest of Bengal in the early 13th century. He led the Khalji army in the conquest of Bihar and Bengal, and his invasion is marked by the destruction of Buddhist monasteries in the region, particularly the renowned Nalanda University.
Step 2: Analyzing the options.
(A) Sailor: This is incorrect. Bakhtiyar Khalji was not known as a sailor.
(B) Traveller: This is incorrect. While many historical figures traveled extensively, Bakhtiyar Khalji is known for his military exploits, not as a traveler.
(C) Physician: This is incorrect. There is no evidence to suggest that Bakhtiyar Khalji was a physician.
(D) Commander: Correct. Bakhtiyar Khalji was a military commander who led conquests in the Indian subcontinent, especially Bengal.
Step 3: Conclusion.
Bakhtiyar Khalji was a military commander, making the correct answer (D) Commander.