In order to restore his Indian kingdom, Humayun sought the assistance of the ruler of Persia. Persia, or modern-day Iran, had historically maintained diplomatic and trade relations with India.

Option 1 - Arabia: Arabia refers to the Arabian Peninsula, which is not geographically close to India. Therefore, it is unlikely that Humayun would have sought the ruler of Arabia for assistance in restoring his kingdom.

Option 2 - Kabul: Kabul is the capital city of Afghanistan. While it is geographically closer to India, the ruler of Kabul is not mentioned historically as someone who helped Humayun restore his kingdom. Therefore, it is unlikely that Humayun sought the ruler of Kabul for assistance.

Option 3 - Persia: Persia, or Iran, had historical ties and diplomatic relations with India. Considering these ties, it is plausible that Humayun sought the assistance of the ruler of Persia in restoring his Indian kingdom. The answer is correct.

Option 4 - Turkey: Turkey, or the Ottoman Empire as it was known at the time, is geographically distant from India. While the Ottoman Empire had significant influence in the region, there is no historical evidence to suggest that Humayun sought the assistance of the ruler of Turkey in restoring