article: One day a poor farmer was taking a bag of rice to town. Suddenly the bag fell from his horse on the road. He didn't know what to do about it because it was too heavy for him to lift   by himself. He only hoped that somebody would soon pass   by and help him.
  Just at this moment a man riding a horse came up to him. But the farmer was very disappointed when he saw who he was. It was the great man living nearby. The farmer had hoped to ask another farmer or a poor man like him for help.
  But to his surprise, the great man got off his horse as soon as he came nearer. He said to the farmer, "I see you need help, friend. How good it is that I'm here just at the right time," Then he took one end of the bag, the farmer took the other. They together lifted and put it on the horse.
  "Sir," asked the farmer, "how can I pay you?"
  "It's quite easy," the great man answered with a smile, "Wherever   you see anyone in trouble, do the same for him."
question: The farmer didn't lift the bag onto the horse by himself because  _  .
options: the bag was broken the horse went away the bag was too heavy the farmer was ill