Final answer:
The excretory system regulates the volume of water in the blood and eliminates wastes.
Step-by-step explanation:
The correct answer is d) Excretory system. The excretory system, which includes organs such as the kidneys and the urinary bladder, is responsible for regulating the volume of water in the blood and eliminating wastes from the body. The kidneys filter the blood and excrete excess water and waste products in the form of urine. This process helps maintain the balance of fluids and electrolytes in the body.
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