Explanation:

- The Battle of Kanauj, also known as the Battle of Bilgram, was fought in 1540.

- This decisive battle was between the troops of Sher Shah Suri and the Mughal Emperor Humayun.

- Option 1 - 1540: This is the correct year for the Battle of Kanauj, confirming your answer.

- Option 2 - 1524: This year does not correlate with the Battle of Kanauj. It’s a period before Babur established the Mughal Empire in India.

- Option 3 - 1556: This year marks the Second Battle of Panipat, involving different parties.

- Option 4 - 1536: Is generally not associated with any major battles like Kanauj in Mughal history.