I think the answer is the last one; Flame bulb; flat worm.
A flame bulb or a flame cell is a specialized excretory cell found in the simplest fresh water invertebrates, including flatworms, rotifers and nemerteans; these are the simplest animals to have a dedicated excretory system. Bundles of flame cells are called Protonephridia.
Answer:
removal of water molecule between each two units
Explanation:
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It lasts about 90 minutes for a normal person.