Deimachus who was a Greek ambassador came to India during the reign of the Mauryan king, _________.

Correct — D. Deimachus was the envoy of Antiochus I Soter of the Seleucid kingdom, and he came to the court of Bindusara, Chandragupta's son.

The pairing is the whole question, because two embassies are easily swapped. Megasthenes belongs to the previous reign — Seleucus I Nicator sent him to Chandragupta Maurya — while Deimachus belongs to the next one. Greek writers knew Bindusara as Amitrochates.

Why the others are wrong

• (a)
  Shatadhanvan — Shatadhanvan was one of the last Mauryan rulers, generations after the Seleucid embassies. The Greek accounts place Deimachus nowhere near him.
• (b)
  Ashoka — Ashoka's link with the Greek world runs the other way: his Rock Edict XIII names Hellenistic kings as recipients of his dhamma missions, not as senders of envoys to him.
• (c)
  Chandragupta Maurya — Chandragupta Maurya received Megasthenes, sent by Seleucus I Nicator. Swapping these two embassies is the exact error the question is built on.

Mauryan-Hellenistic contact is examined as a table of three pairs, and it is worth learning as one.

Seleucus I Nicator sent Megasthenes to Chandragupta Maurya. Antiochus I Soter sent Deimachus to Bindusara. Ptolemy II Philadelphus of Egypt sent Dionysius to the Mauryan court.

All three wrote about India, and all three survive only through quotation in later Greek and Roman authors — no complete text of any of them has come down to us.

Key facts

• Seleucus I Nicator sent Megasthenes to the court of Chandragupta Maurya.
• Antiochus I Soter sent Deimachus to the court of Bindusara.
• Ptolemy II Philadelphus of Egypt sent Dionysius to the Mauryan court.
• Megasthenes' Indica survives only as fragments quoted by later writers.

Common traps

• Defaulting to Chandragupta because Megasthenes is the ambassador everyone remembers.
• Defaulting to Ashoka because he is the best-known Mauryan, though Bindusara's reign holds this embassy.

No directly related past PYQ was found.