The correct answer is d. it is mainly there to prevent any noxious substance from inner into the gut.
An omentum is a layer of the peritoneum (the serous membrane that lines abdominal cavity) that surrounds abdominal organs. It is known that omentum plays a role in immune responses. Omentum contains the clusters of white blood cells (lymphocytes), called “milky spots” which have the first-line defence role in the immune system. When a noxious substance is present, the "milky spots" induce the release of inflammatory molecules.