On the merchant's advice, he sent an invitation to the King and Princess of Khaistân, together with all their traveling court, down to the very humblest servant, to come and be his guests. For three nights and days a great feast was held in honor of the royal guests. Every evening the king and his nobles were served on golden plates and golden cups. The others were served with silver plates and silver cups, and at each meal they were told to keep the plates and cups as a memento of the evening. Never had anything so splendid been seen. In addition to the daily feasts, there were sports and hunting, dances and amusements of all kinds. On the fourth day the King of Khaistân took his host aside and asked him whether it was true, as he suspected, that Wali Dâd wished to marry his daughter. Wali Dâd, after thanking him very much for the compliment, said that he had never dreamed of so great an honor and that he was far too old and ugly for so fair a lady. But he begged the king to stay with him until he could send for the Prince of Nekabad, who was a most excellent, brave and honorable young man who would surely be delighted to try and win the hand of the beautiful princess.
To this the king agreed, and Wali Dâd sent the merchant off to Nekabad with a number of attendants and with such handsome presents that the prince came at once, fell head over ears in love with the princess, and married her in Wali Dâd's palace amidst great rejoicing.
Then the King of Khaistân and the Prince and Princess of Nekabad went back to their own lands, and Wali Dâd lived to a good old age, befriending all who were in trouble. In spite of his prosperity, he preserved to the end the simple-hearted and generous nature that he had when he was only Wali Dâd, the old bald grass cutter.

Which character had the greatest impact on the development of the story’s theme?

Wali Dâd

Princess of Khaistân/Nekabad

King of Khaistân

The Merchant