Please answer the following question: Read the article and select the best answer. Article: Adrian's "Amazing Race" started early when his parents realized that he, as a baby, couldn't hear a thing, not even loud noises. In a special school for the hearing-impaired, he learned sign language and got to mix with other disabled children. However, the sight of all the disabled children communicating with one another upset his mother. She wanted him to lead a normal life. So after speaking to an advisor, she sent him to private classes where he learned to read lips and pronounce words. Later on, Adrian's parents decided to send him to a regular school. But the headmaster tried to prevent them from doing so, saying regular school couldn't take care of a special needs students. His parents were determined to take the risk and push him hard to go through his work everyday because they wanted to prove that, given the opportunity, he could do anything. Adrian made the grade and got accepted. It was a big challenge. The pace was faster so he had to sit at the front of the class and really pay attention to the teacher, which wasn't always easy. But he stuck to it and did a lot of extra work after school. The efforts made by Adrian and his parents paid off. Adrian graduated with good grades and got into a top high school. He also achieved a lot in life outside school. He developed a love for the outdoors and went to Nepal to climb mountains. He even entered the World Yacht Race 05/06--- being the first hearing-impaired Asian to do so. But none of these achievements would have been possible without one of the most important lessons from his mother." "If you believe in yourself and work hard, you can achieve great results." she often said. Question: How did Adrian finally succeed in his study? Options: A: He did a lot of outdoor activities. B: He was pushed hard to study every day. C: He attended private classes after school. D: He worked very hard both in and after class.
A:
D