All of the following organs in the human body are located on both the right and left sides, except ?

Most major organs in the human body are paired, meaning they exist on both the right and left sides of the body to ensure balance, efficiency, and survival even if one organ fails. Examples include the lungs, kidneys, and eyes. However, the spleen is an unpaired organ, as it is located only on the left side of the human body, just beneath the rib cage and above the stomach in the left upper quadrant of the abdomen.

The lungs are a pair of vital respiratory organs — one on each side of the chest cavity — that exchange oxygen and carbon dioxide. Similarly, the kidneys are a pair of bean-shaped organs located on either side of the spine, responsible for filtering blood and producing urine. The eyes are also paired organs located symmetrically on the face, enabling depth perception and a wide field of vision.

In contrast, the spleen is a single organ with essential roles in blood filtration, immune response, and the storage of red blood cells and platelets. It helps remove old or damaged blood cells from circulation and produces white blood cells (lymphocytes) that fight infections. Because of its unique function and structure, the spleen does not require a counterpart on the right side of the body.

Other organs that are unpaired like the spleen include the heart, liver, and stomach, each located on one side of the body with specific purposes. However, the spleen stands out as the main organ associated with the immune and circulatory systems located solely on the left side.

Therefore, among the options given, the correct answer is the spleen, as it is not located on both sides of the body but only on the left.