Explanation:

- Observation: Managers closely watch how processes and teams function in real scenarios, gaining insights into effective strategies and areas for improvement.

- Experimentation: Through trial and error, managers test different approaches within their businesses to find the most effective solutions, leading to theories and general principles.

- Personal Experiences of the Manager: Individual experiences of managers play a significant role in shaping management styles and developing principles, informed by past successes and failures.

- All of the above: Managing effectively often combines observed practices, experimental adjustments, and personal experiences, contributing to a well-rounded approach.