Answer the following question: Read the following article and select the best answer. Article: Once there was a little orphan who always wished that he could fly like a bird. It was very difficult for him to understand why he could not fly. There was another little boy who was _ . One day the orphan came to a park, where he saw the little crippled boy playing in the sand alone. He ran over to the little crippled boy and asked him if he had ever wanted to fly like a bird. "No," he said. "But I've been thinking about what it would be like to walk and run like others." "That is very sad," said the little orphan. "Do you think we could be friends?" "Sure," said the little crippled boy. The two little boys played for hours. Neither of them felt as lonely as they had been before. Then the little crippled boy's father came with a wheelchair to pick up his son. The little orphan ran over to him and said something into his ear. "That would be OK," said the man. The little orphan ran back to his friend and said, "You are my only friend and I wish I could do something to make you walk and run like others. Unluckily, I can't. But there is something that I can do for you." The little orphan boy turned around and told his friend to slide onto his back. Then he began to run across the grass. He ran faster and faster, carrying the little crippled boy on his back. The father began to cry with tears as his son shouted at the top of his voice, "I'm FLYING! Daddy, I'm FLYING!" Question: Why did the little crippled boy's father cry? - Because the orphan boy became his son's only friend. - Because his son was able to fly. - Because he was happy to see his son's excitement. - Because the orphan boy was riding on his son's back.
Answer:
Because he was happy to see his son's excitement.