Final answer:
The athlete donating bone marrow is fulfilling the need for self-transcendence, a level beyond self-actualization on Maslow's hierarchy of needs, indicating a form of altruism.
Step-by-step explanation:
According to Maslow's hierarchy of needs, a 23-year-old athlete donating bone marrow to help a child with leukemia could be fulfilling his need for self-transcendence. This level is proposed to be above self-actualization and pertains to finding meaning and purpose beyond one's own concerns. The athlete's act can be seen as an example of altruism, a form of prosocial behavior that goes beyond basic needs and reflects a concern for the welfare of others.