The correct answer is C. Vaishali.
Vaishali was an ancient city in the Indian subcontinent. It was one of the most important cities of the Vajji Sangh, an ancient Indian republic. Vaishali was located on the banks of the Ganges River in what is now the Indian state of Bihar.
Vaishali was founded in the 6th century BCE by the Licchavi clan. It became a major center of trade and commerce. The city was also a center of learning and culture. Vaishali was home to many Buddhist monasteries and temples.
Vaishali was an important city in the history of India. It was the site of many important events, including the First Buddhist Council and the Second Buddhist Council. Vaishali was also the birthplace of many important Buddhist figures, including Mahavira and Gautama Buddha.
Vaishali declined in importance after the 6th century CE. It was sacked by the Huns in the 5th century CE and by the Turks in the 12th century CE. The city was abandoned in the 13th century CE.
Today, Vaishali is a small town in the Indian state of Bihar. The ruins of the ancient city can still be seen. Vaishali is a popular tourist destination.