Final answer:
Without additional context, it is not possible to accurately determine if Sonja's belief of being the procuring cause of a sale is justified or if her broker should file an ethics complaint. Procuring cause is a real estate term that would pertain to the agent whose actions lead directly to the sale of a property.
Step-by-step explanation:
The question is concerning whether it is true or false that Sonja believes she was the procuring cause of a sale at XYZ Realty and so her broker files an ethics complaint on her behalf. The term procuring cause refers to a real estate agent's actions that directly lead to a sale being completed. If Sonja was indeed the primary agent responsible for a client's decision to purchase a property, and her efforts were uninterrupted and led to the successful transaction, she could be considered the procuring cause. However, the question as stated doesn't provide enough context to determine a true or false answer accurately. It is stating a belief held by Sonja and an action taken by her broker, which requires specific information about the situation to assess.