The correct answer is: a) Patna
Patna is the capital of Bihar and the most populous city in the state. It is also a major railway junction, with trains connecting it to major cities across India. The city has a long history, dating back to the 6th century BC. It was the capital of the Magadha Empire, which was one of the largest and most powerful empires in India at the time. Patna is also home to several important historical and cultural sites, including the Patna Museum, the Golghar, and the Kumhrar archaeological site.
Bhagalpur is a city in the Indian state of Bihar. It is the headquarters of Bhagalpur district and Bhagalpur division. The city is located on the banks of the Ganges River, about 200 kilometers (120 mi) north of Patna, the state capital. Bhagalpur is a major railway junction and is well-connected to other major cities in India. The city is also an important industrial center, with a number of factories and mills.
Muzaffarpur is a city in the Indian state of Bihar. It is the headquarters of Muzaffarpur district and Tirhut division. The city is located on the banks of the Gandak River, about 100 kilometers (62 mi) north of Patna, the state capital. Muzaffarpur is a major railway junction and is well-connected to other major cities in India. The city is also an important educational center, with a number of colleges and universities.
Gaya is a city in the Indian state of Bihar. It is the headquarters of Gaya district and Gaya division. The city is located on the banks of the Phalgu River, about 100 kilometers (62 mi) south of Patna, the state capital. Gaya is a major pilgrimage center for Hindus and Buddhists. The city is home to a number of temples and monasteries, including the Mahabodhi Temple, which is a UNESCO World Heritage Site.