The capital city of Bihar is:

Muzaffarpur
Bodh Gaya
Patna
Bhagalpur

The correct answer is: c) Patna.

Patna is the capital and the most populous city of the Indian state of Bihar. It is the third-largest city in eastern India after Kolkata and Bhubaneswar. Patna is the 19th-largest city in India, with a population of over 1.7 million in the 2011 census. The city is situated on the southern bank of the Ganges River.

Patna was founded in the 6th century BC by the king of the Magadha Empire, Ajatshatru. The city was originally known as Pataliputra. It was the capital of the Mauryan Empire, the Gupta Empire, and the Pala Empire. Patna was also the capital of the British Indian province of Bihar and Orissa.

Patna is a major center of education, culture, and tourism. The city is home to several universities, including the Patna University, the Nalanda University, and the Indian Institute of Technology Patna. Patna is also home to several museums, including the Patna Museum, the Gandhi Museum, and the Bihar Museum.

The city is well-connected by air, rail, and road. Patna Airport is the main airport serving the city. The city is also well-connected by rail to other major cities in India. Patna Junction is the main railway station in the city. The city is also well-connected by road to other major cities in India.

Patna is a beautiful city with a rich history and culture. It is a popular tourist destination and a major center of education, culture, and tourism.