Final answer:
Managerial decisions are made by managers who may consult operations researchers and management scientists for data and analysis, thus involving all groups in the decision-making process.
Step-by-step explanation:
Managerial decisions are typically made by managers; however, they often rely on insights from operations researchers and management scientists to make informed decisions. Therefore, the correct answer to which group makes managerial decisions would be d. All of the above.
Managers are directly responsible for decision-making within a company. They rely on data, analytics, and research conducted by operations researchers and management scientists to create strategies that are effective and sustainable. While the ultimate decision often lies with the managers, the collaborative effort includes contributions from both operations researchers who use mathematical models and techniques to solve complex problems, and management scientists who apply scientific methods to the study and improvement of management systems.