To answer this question, we need to understand the inputs to project plan execution.
Option A) Work authorization system - This option is incorrect because a work authorization system is an important input to project plan execution. It helps ensure that the right people are assigned to the right tasks and that work is authorized and coordinated effectively.
Option B) Project plan - This option is incorrect because the project plan is a key input to project plan execution. It provides the framework for executing the project, including the scope, schedule, budget, and resources.
Option C) Corrective action - This option is incorrect because corrective action is another important input to project plan execution. It involves taking action to address any deviations or issues that arise during the project execution phase.
Option D) Preventive action - This option is incorrect because preventive action is also an important input to project plan execution. It involves taking action to prevent potential issues or risks from occurring during the project execution phase.
Therefore, the correct answer is Option A. A work authorization system is not an input to project plan execution.