Q: What type of process is responsible for gaseous exchange in alveoli?

The gaseous exchange in alveoli is a type of simple diffusion. During this process, oxygen moves from the air in the alveoli into the capillaries surrounding the alveoli, while carbon dioxide moves from the capillaries into the air in the alveoli. This occurs due to the difference in the concentration gradients of these gases between the alveoli and the surrounding capillaries. Oxygen moves from an area of high concentration (in the alveoli) to an area of low concentration (in the capillaries), while carbon dioxide moves from an area of high concentration (in the capillaries) to an area of low concentration (in the alveoli). Osmosis involves the movement of water molecules across a semi-permeable membrane, and is not involved in the process of gaseous exchange in alveoli. Active transport and passive transport involve the movement of molecules across a membrane with the use of energy and the movement of molecules across a membrane without the use of energy, respectively. Therefore, option A is the correct answer.