The most famous prehistoric site in Bihar, located in the Saran district, is:

Chirand
Bhimbetka
Lahuradewa
Patne

The correct answer is Chirand.

Chirand is a prehistoric site located in the Saran district of Bihar, India. It is one of the most important prehistoric sites in India, and is known for its well-preserved remains of a Mesolithic and Neolithic culture. The site was first excavated in the 1960s, and has since yielded a wealth of information about the early inhabitants of the region.

The Chirand site is located on the banks of the Ganges River, and consists of a series of mounds that were once occupied by human settlements. The earliest occupation at the site dates back to the Mesolithic period, and consists of a small village of hunter-gatherers. The Neolithic occupation at the site dates back to around 2500 BC, and consists of a larger village of farmers.

The Chirand site is significant for a number of reasons. First, it is one of the few prehistoric sites in India that has yielded well-preserved remains of a Mesolithic culture. Second, the site provides important information about the transition from a hunter-gatherer to a farming economy in India. Third, the site is a valuable source of information about the early inhabitants of the Ganges Valley.

The other options are incorrect. Bhimbetka is a prehistoric site located in the Raisen district of Madhya Pradesh, India. Lahuradewa is a prehistoric site located in the Lakhimpur Kheri district of Uttar Pradesh, India. Patne is a prehistoric site located in the Patna district of Bihar, India.