Which Chinese pilgrim visited India during the reign of Chandragupta II Vikramaditya?

The correct answer is A, Fa-Hien. Fa-Hien travelled to India at the turn of the fifth century CE, in the reign of Chandragupta II, to collect Buddhist texts. His account notices the prosperity and mildness of government, the rest houses and hospitals, the state of Pataliputra and Ashoka's palace, and the condition of Buddhist monasteries, though he says little about the king himself.

Option B, Hiuen Tsang, came in the seventh century during the reign of Harshavardhana and studied at Nalanda, so he belongs to a later age. Option C, I-tsing, visited still later, towards the end of the seventh century, and also wrote about Nalanda. Option D, Megasthenes, was not Chinese at all: he was the Greek ambassador of Seleucus Nicator at the court of Chandragupta Maurya, some seven centuries earlier, and his book is the Indica. Keep the traveller tied to his king.