Read the following article and select the best answer. Article: Monty Robert's father was a horse trainer. As a child, Monty often went from one farm to another with his father. Sometimes they didn't have money to pay for food, but Monty still kept hoping to own a horse farm. When he was in school, his teacher asked him to write a paper about his dream. He wrote a seven-page paper. He wanted to have a horse farm one day. He even drew a picture of a horse farm in the paper. The next day he handed it in to his teacher. Two days later, he got his paper back. On the front page was a large red "F" with the words "See me after class". So the boy did and asked his teacher, "Why did I get an F?" The teacher said, "This dream will not come true for a young boy like you. You need a lot of money to own a horse farm. You have to buy the land. You have to pay for a lot of things. There is no way you could ever do it." Then the teacher added, "If you write this paper again with a simpler dream, I will give you a good grade." After school he thought hard about it. At last, he decided to hand in the same paper, making no changes at all. He said to the teacher, "You can keep the F and I'll keep my dream." Many years later, Monty had his own large horse farm. His dream came true. So don't let anyone take away your dreams. Follow your dreams, no matter what they are. Question: Monty's teacher gave him a red "F" because he thought _ . - Monty's handwriting was too bad - Monty copied from another student - Monty's dream was too hard for him to achieve - Monty was not working hard to realize his dream
A:
Monty's dream was too hard for him to achieve