The correct answer is D. Diffusion.
Diffusion is the movement of molecules from an area of high concentration to an area of low concentration. This process is driven by the second law of thermodynamics, which states that entropy always increases over time. In the case of diffusion, entropy increases as molecules move from an area of high concentration to an area of low concentration, because there are more possible arrangements of molecules in the latter state.
Oxygen is a gas that is essential for cellular respiration. It is transported from the lungs to the cells by the blood. When oxygen reaches the cells, it diffuses across the plasma membrane into the cytoplasm. This process is driven by the difference in oxygen concentration between the blood and the cytoplasm. The concentration of oxygen is higher in the blood than in the cytoplasm, so oxygen diffuses down its concentration gradient into the cell.
Osmosis is the movement of water across a semipermeable membrane from an area of high water concentration to an area of low water concentration. This process is driven by the difference in water potential between the two areas. Water potential is a measure of the tendency of water to move from one area to another. It is affected by the concentration of solutes, temperature, and pressure.
Evaporation is the process by which a liquid changes into a gas or vapor. This process is driven by the difference in vapor pressure between the liquid and the gas. Vapor pressure is a measure of the tendency of a liquid to evaporate. It is affected by the temperature and the surface area of the liquid.
Concatenation is the process of joining two or more things together. In the context of this question, concatenation could refer to the process of joining two or more molecules together. This process is not typically used to transport oxygen across a plasma membrane.
Therefore, the correct answer is D. Diffusion.