Final answer:
Heidi, who has started smoking, is at a significantly higher risk of developing lung cancer, as tobacco smoke contains carcinogens that affect the respiratory system. This risk is highlighted by the Surgeon General's warning that states smoking is a leading cause of lung cancer.
Step-by-step explanation:
Heidi has started smoking. Which disease is she at risk of developing? The primary health risk associated with smoking is cancer of the lungs. Tobacco smoke contains several carcinogens which greatly increase the risk of developing lung cancer. Additionally, smoking is the leading cause of chronic obstructive pulmonary disease (COPD) and has a negative impact on the cardiovascular system, possibly leading to diseases such as hypertension or heart disease.
Given the list of options provided in the question, the correct answer is a) Lung cancer. Smoking causes damage to the respiratory system, reducing the elasticity of alveoli, which impairs lung function. This damage increases the risk of developing lung cancer significantly. In fact, the SURGEON GENERAL'S WARNING explicitly notes that smoking causes lung cancer, heart disease, emphysema, and may complicate pregnancy.