Excretion in Planaria takes place by ?

Explanation

Excretion in Planaria takes place through **protonephridia** (Option B). Protonephridia are a network of tubules with ciliated cells that help regulate the osmotic balance and remove metabolic wastes from the body of flatworms like Planaria. They are a primitive excretory system that plays a role in maintaining the internal environment of these organisms. Malpighian tubules (Option A) are found in insects and are involved in excretion in that group. Metanephridia (Option C) are a type of excretory organ found in some segmented worms. Nephrons (Option D) are functional units of the vertebrate kidney and are not found in planaria or other flatworms.