​in flatworms, functions to ​remove excess water

A) ​nephridium
B) ​Malpighian tubules
C) ​kidneys

Nephridium

Of some invertebrates, an organ that takes up body fluid and expels excess water and solutes through a pore at the body surface.

Flatworms

These are a group of invertebrate animals belonging to the phylum Platyhelminthes, known for their flat, bilateral bodies and lack of body cavity.

Excess Water

A surplus amount of water in an area or system, which can result from heavy rainfall, flooding, or inadequate drainage.