The correct answer is: c) East Champaran district.
Kesaria Stupa is one of the largest Buddhist stupas in the world. It is located in Kesaria, a town in East Champaran district in the Indian state of Bihar. The stupa was built in the 3rd century BCE by Ashoka the Great, the third emperor of the Mauryan Empire. It is a UNESCO World Heritage Site.
The stupa is a large mound of earth that is topped by a dome. It is made of bricks and is covered in a layer of plaster. The stupa is surrounded by a stone railing and a moat. The stupa is said to contain the relics of the Buddha.
The Kesaria Stupa is an important archaeological site. It is a reminder of the Buddhist heritage of India. It is also a popular tourist destination.
The other options are incorrect.
Option (a), Patna district, is incorrect because Kesaria Stupa is not located in Patna district. Patna district is a district in the Indian state of Bihar. It is the capital of Bihar.
Option (b), Vaishali district, is incorrect because Kesaria Stupa is not located in Vaishali district. Vaishali district is a district in the Indian state of Bihar. It is one of the oldest cities in India.
Option (d), West Champaran district, is incorrect because Kesaria Stupa is not located in West Champaran district. West Champaran district is a district in the Indian state of Bihar. It is the largest district in Bihar.