The correct option is B Caecum
The small intestine is the longest part of the alimentary canal that is divided into three parts, i.e, duodenum, jejunum and ileum.
Whereas the large intestine is divided into three parts i.e., caecum, colon and rectum.
The ileum of the small intestine opens into the caecum, a pouch like structure. Next comes the colon from where salts and fluids are absorbed. Finally, undigested food reaches the third part of the large intestine, the rectum.