Which one among the following rulers established Pataliputra as the capital of the Magadhan Empire ?

According to the official answer key, Ajatashatru is the ruler who established Pataliputra as the capital of the Magadhan Empire. Historically, the early capital of Magadha was Rajgriha (Girivraja) under Bimbisara. However, Ajatashatru recognized the immense strategic value of Pataligrama, situated at the confluence of the Ganges, Gandak, and Son rivers.

• Ajatashatru fortified the village of Pataligrama to serve as a military base (Jaladurga) for his long-drawn campaigns against the Vrijji confederacy and the Lichchhavis.
• This strategic fortification laid the groundwork for the city's emergence as the empire's political center.
• While many historical texts specifically credit his successor, Udayin, with the formal and permanent transfer of the capital, the official key attributes the establishment to Ajatashatru, focusing on his role in founding the site as a seat of power.