Udayin is considered associated with the founding of which city?
Udayin, also written Udayabhadra or Udayin in historical accounts, was an important ruler of Magadha in the Haryanka line. He is traditionally associated with establishing Pataliputra, the city later known as Patna, at or near the confluence of the Ganga and Son rivers. Its location was strategically useful for communication, trade, agriculture, and control over the expanding Magadhan kingdom. Pataliputra eventually became one of the most important political centres of ancient northern India.
Choice A is correct because Pataliputra is the city linked with Udayin’s foundation in the usual school-level account. The other choices belong to different historical settings: Lahore is associated with later regional and imperial histories, Jaipur was founded much later by Sawai Jai Singh II, and Hyderabad was founded in the medieval period by Muhammad Quli Qutb Shah. A helpful memory sequence is that Rajagriha was an early Magadhan capital, Vaishali was also important in the region, and Udayin is especially remembered for shifting attention to Pataliputra. The question asks for the traditional association, not a modern city-history debate.