Read the following article and select the best answer. Article: The old man fished alone in a small rowboat and he had gone eighty-four days now without taking a fish. In the first forty days a boy had been with him. But after forty days without a fish the boy's patents had told him that the old man was now bad luck, and ordered the boy to join another boat, which caught three good fish the first week. It made the boy sad to see the old man come in each day with his boat empty and he always went down to help him carry in the fishing lines or take down the old, patched sail. "Santiago," the boy said to him as they dragged up the boat to the sand. "I could go with you again. I've made some money." the old man had taught the boy to fish and the boy loved him. "No," the old man said. "You're with a lucky boat. Stay with them. You must obey your father." "We can be lucky again too. Remember when we didn't catch a fish for 10 days, then caught a big one each day for a month?" said the boy. "Can I offer you a beer on the balcony and then we'll take the stuff home," said the boy. "Why not?" the old man said. "Santiago," the boy said as they sat on the balcony, "If I cannot fish with you, I would like to serve in some way." "You bought me a beer," the old man said, lifting the bottle to his mouth. "Do you remember the first time I took you out to fish?" the old man asked. "I was five. I remember the tail of a huge fish slapping against the boat, the noise of you clubbing him and the sweet blood smell. I remember everything from when we first went together," the boy said. The old man looked at him with his sun-burned, loving eyes. "May I get some sardines for tomorrow? Let me get four fresh ones," said the boy. "One," the old man said. His hope and his confidence had never gone. But now they were freshening like a sea breeze. "Two," the boy said. "Thank you," the old man said. He was too simple to wonder when he had attained modesty. But he knew he had attained it and he knew it was not disgraceful and it carried no loss of true pride. "Tomorrow is going to be a good day with this... Question: Why was the boy forced to stop working for the old man? - It was too dangerous to continue fishing. - It was time for the boy to return to school. - The old man was thought to be a poor teacher. - The boy couldn't earn enough money with the old man.
The answer to this question is:
The boy couldn't earn enough money with the old man.