What additional measure can improve the absorption capacity of a drainage system?

Improving the absorption capacity of a drainage system hinges on enhancing its ability to collect and manage water or other fluids efficiently. Expanding the system's surface area directly contributes to this goal. By increasing the surface area, the system can engage more of the fluid over a larger space, allowing for more effective absorption and drainage. This expansion could involve techniques such as increasing the diameter of pipes, adding more drainage points, or utilizing porous materials that provide a greater interface with the liquid.

Enhancing the surface area can significantly improve the drainage system’s overall performance by allowing for quicker fluid passage through the medium and reducing the risks of overflow or backup, which is critical in maintaining the functionality of drainage systems.

The other options, while they may have their uses in certain contexts, do not directly address the fundamental mechanics of absorption capacity in the same way an increase in surface area does.