C - The boy enjoys the simple life of a shepherd but he is still restless, believing that there must be something else out there.
Santiago left his religious studies to become a shepherd. His reason for doing so was that he wanted to travel and experience new things. However, becoming a shepherd does not satisfy his restlessness. This is shown in his reoccurring dream that urges him to go to the pyramids in search of a treasure. When looking at these options, A, B and D are completely wrong. Other professions would allow him to travel and he does not plan to return to his sheep. He plans to return to Fatima. He is not loyal to his flock of sheep, but he does see that they have a good permanent home before leaving Spain.