Which symptom is typically associated with proptosis?

Proptosis, also known as exophthalmos, is characterized by the abnormal protrusion or bulging of the eyes. This symptom is commonly associated with various conditions, particularly thyroid eye disease (also known as Graves' disease), where inflammation and swelling of the eye muscles and tissue behind the eyes cause them to protrude.

In this context, option C is correct because it directly describes the primary manifestation of proptosis. When evaluating patients, the presence of bulging eyes is significant as it can indicate underlying thyroid dysfunction, certain tumors, or vascular issues. Understanding this symptom is critical for assessing and managing patients who may have conditions that affect the orbit and surrounding structures.