Chanakya was also known as

Many ancient Indian scholars and statesmen carried more than one name -- a family (patronymic) name, a gotra-based name, and sometimes a title earned through an authored work. When a classical text names its own author in its concluding verses, that self-identification is the most reliable link between a historical figure and any alternate names attributed to them.

Chanakya, the principal architect of the Mauryan state and chief minister to Chandragupta Maurya, authored the Arthashastra, the foundational treatise on statecraft and economics. In the concluding verse of the Arthashastra, its author identifies himself as Vishnugupta; tradition and the wider textual record equate this same author with the more familiar names Chanakya (his patronymic) and Kautilya (the name used internally through the text). Vishnugupta is therefore the name directly self-attested in the text as belonging to Chanakya.

The other offered names belong to distinct historical figures, not to Chanakya:

• Bhattasvamin -- a much later commentator who wrote an explanatory gloss (the Pratipadapanchika) on the Arthashastra; a commentator on the text, not its author.

• Rajasekhara -- a Sanskrit poet and dramatist of the 9th-10th century CE, author of works such as the Kavyamimamsa; a court literary figure unconnected in period or role to Chandragupta Maurya's administration.

• Visakhadatta -- the playwright who wrote the Sanskrit drama Mudrarakshasa, dramatizing the political intrigue around Chandragupta's rise with Chanakya as a character; authoring a work about Chanakya is not the same as being Chanakya's own alternate name.

So among the offered names, Vishnugupta uniquely satisfies both the textual self-identification and the historical record.