Option c is the correct answer. Sri Lanka was not a part of Ashoka's empire. The Mauryan Empire at its peak stretched from Afghanistan in the west to Bangladesh in the east, and from the Himalayas in the north to the Deccan plateau in the south. During his reign, Ashoka conquered Afghanistan by defeating Seleucus I Nicator, acquired Bihar by overcoming the Vajji Confederacy, and subjugated Kalinga through the brutal Battle of Kalinga, significantly expanding the Mauryan Empire across present-day India, Pakistan, Bangladesh, Nepal, and parts of Afghanistan.