Which of the following is a common sign of lung cancer?

A persistent cough is a common sign of lung cancer as it can be one of the earliest manifestations of the disease. In individuals with lung cancer, the tumor can irritate the airways or invade surrounding tissues, leading to a cough that may not go away. This cough can become progressively worse over time and may change in character, which often prompts further investigation.

In contrast, frequent sneezing is typically more associated with allergies or upper respiratory infections, and is not generally linked to lung cancer. Headaches can occur for various reasons, but they are not a direct or common symptom of lung cancer. Similarly, nausea, while it can occur in many conditions or as a side effect of treatments like chemotherapy, is not a primary symptom of lung cancer itself. Thus, a persistent cough stands out as a key symptom that warrants further evaluation in the context of lung cancer.