Final answer:
Kidneys are retroperitoneal, which means they are found: Outside the abdominal cavity (Option B). The kidneys are located outside the peritoneal cavity, protected by muscle and fat beneath the diaphragm, and are crucial for filtering blood.
Step-by-step explanation:
The kidneys are retroperitoneal, meaning they are positioned outside the peritoneal cavity.
Specifically, the kidneys are located in the retroperitoneal space between the parietal peritoneum and the posterior abdominal wall, just below the diaphragm.
They are secured in place by a complex network that includes muscle, fat, ribs, and the renal fascia. The right kidney is found just below the liver, while the left is situated below the diaphragm and adjacent to the spleen.
The kidneys are well protected and play a crucial role in filtering the blood; receiving about 25 percent of the cardiac output.
Each kidney is surrounded by layers of fat and a fibrous capsule that help cushion and protect it. Moreover, the kidneys' location at the T12 to L3 vertebral levels further aids in their protection.
Hence, the correct answer is: Outside the abdominal cavity (Option B).