Vishakhadatta is the correct answer because Chandragupta is prominently featured in Vishakhdatta's book.

According to Theravda commentaries and chronicles, the Mauryan king Ashoka convened the Third Buddhist Council at Ptaliputra (today's Patna) under the leadership of the elder Moggaliputta Tissa.

Bindusara was Chandragupta Maurya's son and Asoka the Great's father. He was known as Amitraghata, which means "slayer of all enemies" (ghata).

He appears to have been an officer under Sibyrtius at the time of the treaty between the Greek ruler Seleucus I Nicator and the Indian ruler Chandragupta Maurya.
Megasthenes was a Hellenistic-era Greek historian, diplomat, Indian ethnographer, and explorer.
"Indica" was written by Megasthenes.
Megasthenes served as Seleucus I Nicator's Greek ambassador in the court of Chandragupta Maurya.

The Mauryan dynasty is the oldest. It was founded by Chandragupta Maurya and existed in the Indian subcontinent from 325 to 185 BCE.
Sri Gupta established the Gupta Empire.
The Kushan Empire was a syncretic empire founded in the early 1st century by Yuezhi in the Bactrian territories.
In 75 BCE, Vasudeva Kanva established the Kanva dynasty.

Bindusara was the son of Chandragupta Maurya and the second emperor of the Maurya dynasty. He is thought to have conquered Deccan, a region in southern India.

In Madhya Pradesh, the Maski and Gujara Pillars have inscriptions that refer to Ashoka as Devanampriya or Piyadasi.

Chandragupta Maurya refers to Sandrocottus in classical Greek sources.
Chandragupta Maurya (reigned 322–298 BC) established the Mauryan Dynasty at Patliputra. He deposed the Nanda Dynasty with the assistance of Chanakya.
His vast empire included Bihar, Bengal, Deccan, parts of current Tamil Nadu, North East India, Eastern Afghanistan, Baluchistan, and the area west of the Indus.

Alexander's successor was Seleucus, one of his generals.Megasthenes was dispatched to Chandragupta's Court by Seleucus.
It is believed that Chandragupta Maurya spent his final days in Shravanabelagola.
He is thought to have died as a result of his Santhara practice.

305 BCE. After defeating Seleucus in 305 BCE, Chandragupta extended the Maurya Empire's borders toward Seleucid Persia.

Deimachus arrived in India during Bindusara's reign. Syrian King Antiochus-I dispatched his ambassador Deimachus to Bindusara's court. Megasthenes was replaced by Deimachus. The Greek historians who served as ambassadors in the Mauryan court were Megasthenes, Deimachus, and Dionysius.