Final answer:
Option D, 'goals can be accomplished through determination and hard work', best captures the major theme of the text, which emphasizes personal excellence through effort and tenacity.
Step-by-step explanation:
The major theme of the text corresponds to the last quote: "The will to win, the desire to succeed, the urge to reach your full potential: these are the keys that will unlock the door to personal excellence." Therefore, option D, which states 'goals can be accomplished through determination and hard work,' best captures the essence of the theme present in the text. The text emphasizes the importance of personal excellence, which aligns with the idea of achieving goals through consistent effort and tenacity. This is further supported by references to overcoming difficulties, preparation leading to success, and the importance of thinking as part of the learning process.