Concept:The Garuda pillar at Besnagar is a historical monument that marks early cultural and religious exchange between Greeks and Indians.Key Fact:Heliodorus, a Greek ambassador from the court of Indo-Greek king Antialcidas, erected the Garuda pillar at Besnagar (Vidisha, Madhya Pradesh) around the 2nd century BCE.Explanation:Heliodorus was sent to the court of the Shunga king Bhagabhadra. He dedicated the pillar to Vasudeva (Vishnu), as recorded in a Brahmi inscription. The pillar is topped with a Garuda, Vishnu’s vehicle. This makes Heliodorus a foreigner who adopted Vaishnavism. Menander was a Buddhist king, Pushyamitra Sunga was a Shunga ruler, and Kanishka was a Kushan emperor who patronized Buddhism. None of them erected this pillar.Answer:C. Heliodorus