The correct answer is (a) Saral Nahar Rai.
Saral Nahar Rai is a site located in the Sonbhadra district of Uttar Pradesh, India. It is a prehistoric site that has been dated to the Mesolithic period. The site is known for its human burials, which have been found in single and multiple graves. The human skeletons found at Saral Nahar Rai are well-preserved and provide valuable information about the physical characteristics of the people who lived in the area during the Mesolithic period.
The other options are incorrect. Damdama is a site located in the Gurgaon district of Haryana, India. It is a prehistoric site that has been dated to the Neolithic period. The site is known for its stone tools and pottery. Mahadaha is a site located in the Etah district of Uttar Pradesh, India. It is a prehistoric site that has been dated to the Chalcolithic period. The site is known for its copper tools and pottery. Langhnaj is a site located in the Mehsana district of Gujarat, India. It is a prehistoric site that has been dated to the Harappan period. The site is known for its terracotta figurines and beads.