Final answer:
The membranes that hold the internal organs in place in coelomates are called mesenteries. These structures are crucial for supporting the intestines and other abdominal organs by forming serous membranes.option a is correct answer.
Step-by-step explanation:
The membranes that hold the internal organs in place in coelomates are called mesenteries. Coelomates, also known as eucoelomates, are triploblastic animals that possess a true coelom, which arises entirely within the mesoderm germ layer.
The coelom is an epithelial-lined cavity that is filled with fluid, lying between the digestive system and the body wall, and it provides several functional advantages including protection, space for organ growth and movement, and efficient nutrient circulation.
The peritoneum is a specific example of a serous membrane in the abdominal cavity that holds digestive organs in place, which is part of the mesenteries. Serous membranes such as the peritoneum, pleura, and pericardium are all formed from mesodermally-derived epithelium called the mesothelium. These serous membranes are vital for reducing friction between organs by secreting a lubricating serous fluid.