Final answer:
According to Fiedler's contingency studies, the most effective leadership style for organizations that were considered 'moderately favorable' is the c. selling style. It involves direct involvement in decision-making and providing explicit instructions and guidance to followers.
Step-by-step explanation:
According to Fiedler's contingency studies, for organizations that were considered 'moderately favorable' in terms of leaders' authority, task definition, and leader-member relationships, the most effective style for the leader to have is the selling style.
The selling style is characterized by leaders who are directly involved in decision-making and provide explicit instructions and guidance to their followers. This style is effective in situations where followers have a moderate need for leadership and benefit from a structured environment with clear responsibilities and little ambiguity.