Final answer:
B. He realized that he wanted to work in the American education system.
Moises Urena's story indicates that he wanted to work in the American education system, inspired by his experience of learning to read as a first grader.
Step-by-step explanation:
Based on Moises Urena's personal story, the option that best represents what ultimately changed about his life is B. He realized that he wanted to work in the American education system. This is evident from the excerpts where learning to read as a first grader inspired him to become a teacher to share his experiences with future first graders. His story highlights themes such as changing, adapting, trying new things, making a difference, and inspiring people. Urena's journey showcases a significant transformation in his aspirations and goals, leading him to pursue a career in education to share his experience with reading and impact the lives of young students.