The correct answer is (a) Hieun Tsang.
Hieun Tsang was a Chinese Buddhist monk who traveled to India in the 7th century CE. He visited Nalanda University, where he studied for several years. He wrote extensively about his experiences in India, including his time at Nalanda. His writings provide valuable insights into the history and culture of India at that time.
Fa Hien was another Chinese Buddhist monk who traveled to India in the 5th century CE. He also visited Nalanda University, but he did not stay there as long as Hieun Tsang did. His writings about India are less detailed than Hieun Tsang’s, but they still provide valuable information about the country at that time.
Megasthenes was a Greek historian who lived in the 4th century BCE. He was sent by Alexander the Great to India as an ambassador. He wrote a book about India called Indica, which is an important source of information about the country at that time. However, there is no evidence that he ever visited Nalanda University.
Therefore, the correct answer is (a) Hieun Tsang.