Final answer:
The question about the workload entry project code used exclusively in a deployed theatre cannot be answered without further context or specific operational guidelines.
Step-by-step explanation:
The question does not provide enough context or information to accurately determine which workload entry project code is used exclusively in a deployed theatre. This type of question is typically related to military or government operations, as project codes are often used for classification and management of tasks in these sectors. Without specific guidance documentation or additional context that might come from a manual or a set of regulations, it's not possible to accurately answer which project code (Code A, Code B, Code C, or Code D) is used in a deployed theatre only.