Nalanda University flourished during the reign of which

Solution

Nalanda was an acclaimed Mahavihara, a large Buddhist monastery in the ancient kingdom of Magadha in India. The site is located about ninety five kilometres southeast of Patna near the town of Bihar Sharif and was a centre of learning from the fifth century CE to c. 1200 CE. Nalanda flourished under the patronage of the Gupta Empire in the 5th and 6th centuries, and later under Harsha, the emperor of Kannauj. Hence option D is the correct answer.