Final answer:
Mary McLeod Bethune's passion for learning, sparked by her ability to read from an early age, indicates a strong aptitude for teaching, which led her to become a prominent educator and college founder.
Step-by-step explanation:
The detail from Mary McLeod Bethune's early life that most suggests her aptitude for teaching is B) The early nurturing of her passion for learning. This is highlighted by her desire to become a teacher after learning to read in the first grade, as she wanted to share her experiences with future first graders. Her profound appreciation for education and its power to empower people is evident in her path to becoming a revered educator and founder of a college in Florida. Additionally, her experiences leading schools and advocating for black equality while dealing with racial challenges also showcase her effective communication skills and assertiveness, essential traits for a career in teaching.