Prolonged exposure to pollutants, such as cigarette smoke, degrades the walls of the alveoli, making them inelastic. this condition is called  .

Emphysema

Explanation:

Emphysema is a slowly evolving chronic respiratory irritation often caused by smoking, although other agents (dust, pollutants, chemical vapors) may also cause it. In emphysema, the alveoli become elastic and turn into large air-filled sacs that make it difficult for air to come into contact with the blood, since the tissue through which the vessels passed was destroyed.

In emphysema, the alveoli become compromised and lose the ability to supply oxygen to the blood and to remove carbon dioxide from it. Healthy alveoli are tiny, numerous, spongy and elastic. In emphysema, they are larger, less numerous and comparatively more rigid. In the advanced stages of the disease, the person is unable to perform even insignificant physical activities and may require supplemental oxygen. In such cases, emphysema can be fatal.

c. emergency contraception

explanation:

used for after unprotected intercourse