Which of these fits gap (iv)?

Directions: Complete this passage by choosing the most suitable word/phrase from each list to fit the corresponding gap.

One day a crow stole a piece of cheese. The crow was just going to eat the cheese when a fox (i)____ along and thought of taking away the cheese. He asked the crow for it, but the crow did not (ii)_____ as he had the cheese in his beak and he did not want to drop it. “What a fine bird you are,” said the fox. The crow was very pleased (iii)____ hear this, but still said nothing. “I've been told that the song of crow is very sweet. (iv)____ you sing for me?” said the fox,” It will make me very happy.” The crow cawed and down fell the cheese. The fox picked it up quickly and ran away.