The correct answer is B. Chandragupta II. Fa-hien (Faxian), the Chinese Buddhist pilgrim, visited India during the reign of Chandragupta II (also known as Chandragupta Vikramaditya) of the Gupta dynasty. He arrived around the early 5th century CE, seeking Buddhist texts and studying the practices of Buddhism in India. His travel accounts provide valuable information about Gupta India’s society, administration, and Buddhism. The other rulers listed do not align with the period of Fa-hien’s visit.