Final answer:
The Hersey-Blanchard leadership model includes participating, delegating, and selling leadership styles; therefore, 'buying' is not a style associated with this model. Option d.
Step-by-step explanation:
The leadership styles that are part of the Hersey-Blanchard Situational Leadership Model include participating, delegating, and selling. These styles correspond to varying degrees of task behavior and relationship behavior that a leader must provide based on the maturity level of the followers. The participating style involves shared decision-making and a high degree of supportive behavior, the delegating style involves low supportive and directive behavior as followers are able and willing to take responsibility, and the selling style involves high directive behavior combined with high supportive behavior as followers are willing but not able to take on responsibility. These styles contrast with the other styles of leadership such as democratic, authoritarian, and laissez-faire, which are related but not part of this specific model. Therefore, buying(d) is not a leadership style identified within the Hersey-Blanchard leadership model.