Final answer:
The opening of the large intestine, which attaches to the appendix, is called the cecum. The cecum is the first segment that receives waste material from the small intestine.
Step-by-step explanation:
The opening of the large intestine is called the cecum. The cecum is the first part of the large intestine where waste enters from the small intestine. It is where the appendix is attached, indicating that the answer to the question 'Which part of the large intestine attaches to the appendix?' is a. cecum. After the cecum, the large intestine continues with the ascending colon, transverse colon, descending colon, and sigmoid colon, eventually leading to the rectum and finally the anus, which is the exit point for fecal matter.
Therefore, the correct answer to the original question 'The opening of the large intestine is called the?' is a. cecum.