Who was the last ruler of India that adopted Jainism in his last days?

Answer: Option C

According to Jain history, late in his life, Chandragupta adopted Jainism, renounced the empire he built and handed over his power to his son, became a Jaina monk, and headed to meditate and pursue spirituality in the Deccan region, under the Jaina teacher Bhadrabahu at Shravanabelagola.