Final answer:
The mesenteries are important for supporting and stabilizing organs within the abdominopelvic cavity, and they contain blood vessels, lymphatic vessels, and nerves supplying the organs. The correct function is option B.
Step-by-step explanation:
The mesenteries are structures within the abdominopelvic cavity that are crucial for maintaining the position and stability of abdominal organs. They provide support and prevent the intestines and other abdominal organs from becoming entangled during movements of the body or intestines. These formations are made up of two layers of peritoneum with connective tissue in between, and contain blood vessels, lymphatic vessels, and nerves that supply the encased organs. The mesenteries help to organize the organs and keep them in place, ensuring optimal function.
The correct answer to the question regarding the function of the mesenteries is that they support and stabilize organs in the abdominopelvic cavity, option B. They do not primarily serve as a layer of insulating fat, nor do they divide the abdominal cavity from the pelvic cavity. Hence, options A and C are not the correct functions of the mesenteries, and option D is incorrect as it indicates that all the options are functions of the mesenteries.