Final answer:
Emphysema reduces alveolar surface area, leading to decreased efficiency in gas exchange and difficulty in breathing due to trapped air in the lungs.
Step-by-step explanation:
Emphysema is a chronic lung disease that primarily occurs due to smoking tobacco, where the walls of the alveoli are damaged and destroyed. This destruction leads to a significant decrease in the surface area available for gas exchange. This reduction in alveolar surface area causes a decrease in the overall efficiency of the respiratory system. Hence, the likely effect of emphysema on the respiratory system is c) Decreased surface area for gas exchange. This impairment leads to difficulty in breathing and the inability to adequately expel air from the lungs, often resulting in trapped air and reduced oxygen uptake.