The founder of the Sultanate of Gujarat was Zafar Khan, which makes option 4 the correct answer. Zafar Khan was a governor appointed by the Delhi Sultanate, and he declared himself independent in 1407. As an independent ruler, he established the Sultanate of Gujarat and took the title of Muzaffar Shah. He ruled from 1407 to 1410.

Option 1, Ahmad Shah, is not the correct answer. Ahmad Shah was a later ruler of the Sultanate of Gujarat. He ruled from 1411 to 1442, succeeding Muzaffar Shah.

Option 2, Muhammad Shah, is also not the correct answer. There were rulers with the name Muhammad Shah in different dynasties and periods, but none of them were the founders of the Sultanate of Gujarat.

Option 3, Dilawar Khan, is not the correct answer either. Dilawar Khan was a noble in the Delhi Sultanate, but he did not establish the Sultanate of Gujarat.

In conclusion, Zafar Khan, also known as Muzaffar Shah, was the founder of the Sultanate of Gujarat, making option 4 the correct answer.