Which part of the large intestine does the ileum open into?

The ileum, which is the final part of the small intestine, connects to the large intestine at the cecum. This connection is facilitated by the ileocecal valve, which helps to regulate the flow of materials from the ileum into the cecum while preventing backflow. The cecum serves as the beginning of the large intestine and plays a vital role in absorbing fluids and salts that remain after the digestion of food in the small intestine. This structural and functional relationship is critical for proper digestive processes and absorption. Therefore, the cecum is the correct answer regarding where the ileum opens into the large intestine.