The correct answer is D. Decision analysis.

According to Peter Drucker, the following are the activities to be performed while determining the organizational structure:

  1. Relations analysis. This involves identifying the key relationships within the organization, such as those between managers and subordinates, between departments, and between the organization and its environment.
  2. Situational analysis. This involves assessing the organization's current situation, including its strengths, weaknesses, opportunities, and threats.
  3. Activities analysis. This involves identifying the activities that need to be performed in order to achieve the organization's goals.
  4. Structure analysis. This involves designing an organizational structure that will enable the organization to perform its activities effectively.

Decision analysis is not one of the activities to be performed while determining the organizational structure. This is because decision analysis is a process that is used to make decisions, not to design organizational structures.