The correct answer is option 3 and the region of India that was ruled by Sultan Zain-ul Abidin is Kashmir. Sultan Zain-ul Abidin, also known as Zain-ul-Abidin, reigned as the Sultan of Kashmir from 1420 to 1470. He was a ruler from the Shah Mir dynasty, which ruled over Kashmir for several centuries.
Option 1, Assam, is incorrect as Sultan Zain-ul Abidin did not rule over Assam. Assam is a state in northeastern India, historically ruled by various dynasties and kingdoms such as the Ahom Kingdom.
Option 2, Delhi, is also incorrect. While Delhi has been an important center of power and has seen many rulers throughout history, Sultan Zain-ul Abidin did not have authority over this region.
Option 4, Orissa, is not the correct answer either. Orissa, now known as Odisha, is a state in eastern India and has had its own rulers and dynasties, and Sultan Zain-ul Abidin was not one of them.
Therefore, the correct answer is option 3, Kashmir, where Sultan Zain-ul Abidin ruled during the 15th century.