Final answer:
The four organs involved in fluid output are the kidneys, lungs, skin, and intestines, each playing a critical role in waste excretion and homeostasis.
Step-by-step explanation:
The four organs from which fluid output occurs are the kidneys, lungs, skin, and the intestines. These organs are critical for the excretion of wastes and maintaining the body's homeostasis.
The kidneys are the main osmoregulatory organs, filtering blood to form urine, which is then expelled through the urinary system, which includes the ureters, urinary bladder, and urethra. The lungs expel carbon dioxide and water vapor, while the skin releases sweat, and the intestines eliminate fluids within fecal matter.