The Arthashastra is an ancient Indian Sanskrit treatise that deals primarily with statecraft, economic policy, administration, diplomacy, taxation and military strategy, and it stands as one of the world's earliest comprehensive manuals of governance.

It was authored by Kautilya, also known as Chanakya or Vishnugupta, who served as the chief minister, adviser and mentor of the Mauryan emperor Chandragupta Maurya and is traditionally credited with helping him found the Mauryan Empire around the 4th century BCE.

The work systematically advises a ruler on how to acquire, maintain and consolidate power, run an efficient bureaucracy and intelligence network, manage the treasury and trade, and conduct war and foreign policy through devices such as the mandala theory of inter-state relations.

Considering the wrong options: Ashoka was the great Mauryan emperor, grandson of Chandragupta, famous for his edicts and the spread of Buddhism after the Kalinga war, but he did not write this text.

Visakhadatta was a later Sanskrit dramatist who wrote the play Mudrarakshasa, which dramatises Chanakya's political intrigues but is a work of literature, not the Arthashastra itself. Megasthenes was a Greek ambassador sent by Seleucus Nicator to Chandragupta's court, and he described India in his account Indica, not in the Arthashastra.

Hence, the author of the Arthashastra was Kautilya.