The correct answer is: b) Bamboo and thatch.
Bhelaghar is a temporary structure made of bamboo and thatch that is constructed by young men during the Bohag Bihu festival. It is a place where young men gather to sing, dance, and celebrate the festival. The structure is usually built in a public place, such as a field or a park. It is often decorated with flowers and lights.
The other options are incorrect because they are not materials that are typically used to construct Bhelaghar. Clay and mud are not strong enough to support the weight of the structure, and cloth and wood are not durable enough to withstand the elements. Metal and stone are too heavy and expensive to be used for this purpose.
Bhelaghar is an important part of the Bohag Bihu festival. It is a place where young men can socialize and celebrate the festival. It is also a place where they can learn about their culture and traditions.