Final answer:
Bob's desire to engage in downhill mountain biking is best explained by Maslow's Hierarchy of Needs as an expression of self-actualization, which is the fulfillment of one's full potential once basic needs have been met.
Step-by-step explanation:
Bob's need to go downhill mountain biking to achieve an internal feeling of satisfaction can be best explained by Abraham Maslow's Hierarchy of Needs. This need is reflective of the self-actualization tier, which is at the top of Maslow's pyramid. Self-actualization involves realizing one's full potential and participating in activities that foster personal growth and fulfillment. In the context of Maslow's theory, once physiological and safety needs are met, individuals strive to fulfill their higher-level needs, with self-actualization being the peak experience where one finds true personal gratification.
Maslow's model proposes that lower-level needs such as food and shelter must be satisfied before higher-level needs like self-worth and self-actualization can influence behavior. In Bob's case, provided his basic needs are met, his desire to go mountain biking suggests he is seeking to satisfy his higher-level needs for self-fulfillment and personal enjoyment, hallmarks of self-actualization.