Final answer:
Simple squamous epithelium is the type of epithelial tissue that forms thin serous membranes, allowing for rapid diffusion and filtration.
Step-by-step explanation:
The type of epithelial tissue that forms thin serous membranes is simple squamous epithelium. This type of tissue consists of a single layer of flattened and thin cells. The simple squamous epithelium is specifically adapted for rapid diffusion and filtration due to its thinness. It forms the lining of body cavities, blood vessels, and organs. For instance, the mesothelium is a type of simple squamous epithelium that lines the body's serous cavities and secretes a lubricating fluid.