Concept:Underground drainage removes excess soil water through buried perforated pipes or tiles.
Explanation:In underground drainage, perforated pipes or tiles are laid below the root zone.
These tiles have small holes that allow excess water from the surrounding soil to seep inside.
The collected water then flows through the tiles to an outlet, where it is safely discharged.
Options A and C describe open ditches and furrows, which are surface drainage methods.
Option B describes bringing water onto the farmland, which is irrigation, not drainage.
Only Option D correctly describes the working of underground tile drainage.
Answer:D. Water seeps into tiles to reach an outlet where it is discharged.