The correct answer is: a) Indo-Roman trade.
Arikamedu is an archaeological site located in the Pondicherry district of India. It is a significant site for the study of Indo-Roman trade. The site was first excavated in the early 20th century, and has since yielded a wealth of artifacts, including Roman pottery, coins, and glassware. The presence of these items at Arikamedu provides clear evidence of the trade that took place between India and Rome during the early centuries AD.
Option b) Early historic urban life is incorrect. While Arikamedu was an important trading center, it was not a large city. The site is relatively small, and there is no evidence of large-scale urban planning.
Option c) Megalithic culture is incorrect. Megalithic monuments are large stone structures that were built by prehistoric peoples. There is no evidence of megalithic monuments at Arikamedu.
Option d) Paleolithic settlements is incorrect. The Paleolithic period is the earliest period of human prehistory, and is characterized by the use of stone tools. There is no evidence of Paleolithic settlements at Arikamedu.