Who among the following envoys was sent by Seleucus I to the court of Chandragupta Maurya?

The correct option is Megasthenes.

Step-by-Step Explanation:
1. Historical Context: After the death of Alexander the Great, his general Seleucus I Nicator founded the Seleucid Empire. Around 305 BCE, Seleucus I engaged in a conflict with Chandragupta Maurya, the founder of the Mauryan Empire in ancient India.
2. Diplomatic Treaty & Envoy: Following a peace settlement between the two rulers, Seleucus I established diplomatic ties with the Mauryan court and sent Megasthenes as his official envoy/ambassador to Chandragupta Maurya's capital at Pataliputra (modern-day Patna).
3. Historical Significance: During his time in India, Megasthenes recorded detailed observations about the Mauryan administration, society, economy, and culture in his famous work titled Indika.

Analysis of Other Options:
• Fa-Hien: A Chinese Buddhist traveler who visited India centuries later during the reign of Chandragupta II (Gupta Dynasty) in the early 5th century CE.
• Deimachus: A Greek ambassador sent by Antiochus I (the son of Seleucus I) to the court of Bindusara, who was Chandragupta Maurya's son and successor.
• Al-Biruni: A Persian polymath who came to the Indian subcontinent in the 11th century CE accompanying Mahmud of Ghazni and wrote Kitab al-Hind.