What are common causes of blood-streaked sputum?

Blood-streaked sputum, also known as hemoptysis, can arise from various underlying conditions, and option C presents some of the most significant causes related to this symptom. Tumors, particularly lung cancer, can lead to the experience of blood in the sputum as the cancerous growth may invade blood vessels in the lungs. Tuberculosis, a serious infectious disease, can cause destructive changes in lung tissue, which may also result in bleeding and subsequent hemoptysis. Pulmonary edema, characterized by fluid accumulation in the lungs, can cause irritation and damage to the lung tissue, leading to the presence of blood in sputum. Additionally, severe coughing can lead to trauma in the airways, resulting in blood-streaked sputum due to minor injuries to the tissues.

In comparison, while the other options mention valid respiratory conditions, they do not primarily result in hemoptysis as consistently or significantly as those listed in option C. Asthma, influenza, and other respiratory issues can lead to inflammation and mucus production, but are less commonly associated with the presence of blood in sputum. Thus, option C best encompasses the most relevant and serious causes of blood-streaked sputum.