When senior managers at Gap, Inc. decided to become the number one service-quality clothing company in the world, they were engaging in the management function of .

Planning

Explanation:

Planning is crucial aspect of management, it can be explained as the process carried out by an organization to make rooms for their activities in the future for the success of the organization, it helps the organization to know the goals and how to achieve this goals. It should be noted that Planning could be strategic or operational in nature

Therefore, from the question, the statement can be written as " when senior managers at Gap, Inc. decided to become the number one service-quality clothing company in the world, they were engaging in the management function of planning"