Final answer:
Alveolar macrophages are responsible for removing tiny dust particles from alveolar surfaces, keeping the gas exchange areas clear and functional. The correct option is 2.
Step-by-step explanation:
The tiny dust particles on the alveolar surfaces are primarily removed by macrophages. While cilia and mucus play a vital role in trapping and moving debris out of the airways, it is the alveolar macrophages that actively engulf and digest the dust particles and other debris in the alveoli, which are tiny air sacs in the lungs.
The function of alveolar macrophages is particularly important because the alveoli are where gas exchange occurs, and it's crucial for them to remain clear to function efficiently. Option 2. is the correct one.