Which of the following structures functions as an excretory, system found in flatworm?

The structure that functions as an excretory system found in flatworms is the flame cell. Flame cells are specialized cells that are lined with cilia, and they help to remove waste materials and excess water from the body of the flatworm. As fluid is moved through the flame cells, the cilia create a flickering effect that looks like a flame, hence the name "flame cell." The waste materials are then transported out of the body through a system of tubules and ducts. Other organisms such as planarians also have flame cells as their excretory system.