Option d is the correct answer. The Lakshmana Era, a new samvat, was initiated by Lakshmana Sena, a ruler of eastern India from 1178 to 1206. This year-numbering system is believed to have started around 1118-1119 AD, sixty years before the beginning of Lakshmana Sena's rule. The exact reason for selecting this particular year is debated among historians, with some suggesting it might be Lakshmana Sena's birth year. The era's start has been deduced from various sources, including Abul Fazl's Akbarnama and dates mentioned in Sanskrit, Bengali, and Maithili manuscripts, as well as copper-plate inscriptions. This era was used in Bengal and Bihar for dating purposes in manuscripts and historical records for several centuries. Important Tips Prominent Kings of Sena Dynasty: The Sena Dynasty, ruling Bengal from c. 1097 to 1225 CE, held significant iafluence with key rulers: Vijaya Sena (c.1095-1158 CE): Founder of the dynasty, ruled over 60 years, restoring peace and prosperity. Consolidated power in western Bengal, assuming independence from the Palas. Conquered Vanga, defeating Bhojavarman. Notable capitals: Vikrampura and Vijaypura. Complemented by poet Sriharsha's "Vijay Prasasti" and Umapati Dhara's Deopara inscription. Ballal Sena (c.1158-1179 CE): Consolidated kingdom, including parts of Bihar and Mithila. Revived orthodox Hindu practices, linked with Kulinism. Promoted close social ties with South India, marrying Ramadevi of Western Chalukya Empire. Authored "Danasagara" and "Adbhutsagara." Lakshmana Sena (c.1178-1207 CE): Reached zenith of military prowess, expanded empire to Assam, Odisha, Bihar, and possibly Varanasi. Defeated Jayachandra of Gahadavala dynasty. Devout Vaishnav, titled Paramvaishnava, and attracted notable poets to his court. Oversaw cultural growth and learning, completed "Adbhutsagara." Later faced territorial disintegration and invasions by Central Asian Islamic forces.