Explanation:

Recently, Skeletal remains of a child were excavated from Konthagai village, part of the sixth phase of ongoing excavations in the ancient site of Keeladi. Konthagai village, located around 2 km from Keeladi, is believed to be a burial site. Keeladi excavation site is a Sangam period settlement that is being excavated by the Archaeological Survey of India and the Tamil Nadu Archaeology Department. The settlement lies on the bank of the Vaigai River. This site is located 12 km southeast of Madurai in Tamil Nadu, near the town of Keeladi in Sivagangai district. This is a large-scale excavation carried out in Tamil Nadu after the Adichanallur archaeological site. This site is estimated to be from the period between 5th century BCE and 3rd century CE. Hence option 4th is correct.