The correct answer is D) Supportive, participative leadership style. The explanation is as follows: 1. The managers described in the question believe that the average person likes work, willingly assumes responsibility, and is trustworthy. This aligns with the assumptions of Theory Y, which suggests that people are naturally motivated and can be trusted to work towards organizational goals. 2. A manager with such beliefs is likely to adopt a supportive, participative leadership style, which involves involving employees in decision-making, empowering them, and providing support and guidance as needed. 3. The other options are incorrect because they describe more autocratic and directive leadership styles, which would not align with the assumptions of Theory Y.