Final answer:
The structure located in the left lower quadrant of the abdomen is the sigmoid colon, which is distinct from the liver, gallbladder, and duodenum that are located in other quadrants.
Step-by-step explanation:
Among the provided options for the structure located in the left lower quadrant of the abdomen, the sigmoid colon is the correct answer. The liver occupies the upper right quadrant and is involved in digestion and metabolism. The gallbladder, situated under the liver, stores bile but is also located in the right upper quadrant. The duodenum is found in the upper part of the abdomen and serves as the initial section of the small intestine. In contrast, the sigmoid colon, an S-shaped segment of the colon, is placed in the left lower quadrant, where it facilitates the final phase of digestion before transitioning into the rectum.