The correct answer is (b), Pataliputra.
Pataliputra was the capital of the Mauryan Empire and one of the largest cities in the world at the time. It was located on the banks of the Ganges River in what is now the Indian state of Bihar. The city was founded in the 6th century BC by the king Ajatashatru and was later expanded by the emperor Ashoka. Pataliputra was a major center of trade and learning and was home to many temples, palaces, and other important buildings. The city was abandoned in the 12th century AD and its ruins are now a UNESCO World Heritage Site.
Vaisali was an ancient city located in the Indian subcontinent. It was one of the most important cities of the Vajji confederacy, a powerful political and economic union of 16 kingdoms. Vaisali was also a major center of Buddhism and Jainism. The city was abandoned in the 6th century AD.
Kapilavastu was the birthplace of the Buddha. It was located in the Lumbini district of Nepal. The city was abandoned in the 6th century BC.
Sravasti was an ancient city located in the Indian subcontinent. It was one of the most important cities of the Kosala kingdom. Sravasti was also a major center of Buddhism. The city was abandoned in the 12th century AD.