Correct Option: C. Rectum Explanation of the Correct Answer The alimentary canal, also known as the digestive tract, is a continuous tube that runs from the mouth to the anus. It is responsible for the digestion and absorption of food, as well as the elimination of waste. The terminal portion of this canal is the rectum.

1. Location and Function of the Rectum:
2. The rectum is the final section of the large intestine, located just before the anus. It serves as a temporary storage site for feces before they are expelled from the body. The rectum is crucial for the regulation of bowel movements, as it signals when it is time to defecate.
3. Anatomical Context:
4. The alimentary canal consists of several key parts:
   • Mouth: Where digestion begins.
   • Oesophagus: A muscular tube that transports food from the mouth to the stomach.
   • Stomach: A sac-like organ where food is mixed with digestive juices.
   • Small Intestine: Where most digestion and nutrient absorption occurs.
   • Large Intestine: Comprising the cecum, colon, and rectum, it absorbs water and forms feces.
   • Anus: The opening at the end of the alimentary canal through which feces are expelled.

Why the Other Options Are Incorrect

• A. Oesophagus:
• The oesophagus is not the terminal portion; it is the tube that connects the throat (pharynx) to the stomach. Its primary function is to transport food, not to store or eliminate waste.
• B. Stomach:
• The stomach is an organ where food is mixed with gastric juices for digestion. It is located before the intestines in the alimentary canal and is not the final part of the digestive system.
• D. Colon:
• The colon, also known as the large intestine, is the part of the digestive system that follows the small intestine and precedes the rectum. While it plays a significant role in absorbing water and forming feces, it is not the terminal portion; the rectum follows the colon and is the last segment before waste is expelled.

Summary of Key Points

• The rectum is the terminal portion of the alimentary canal in mammals, serving as a storage site for feces.
• The alimentary canal includes the mouth, oesophagus, stomach, small intestine, large intestine (colon), rectum, and anus.
• The oesophagus and stomach are involved in food transport and digestion, while the colon is responsible for water absorption and feces formation, but neither is the final part of the canal.
• Understanding the structure and function of the alimentary canal is essential for grasping how digestion and waste elimination occur in mammals.

Revision Summary

• The rectum is the last part of the alimentary canal, leading to the anus.
• The alimentary canal includes several organs, each with specific functions in digestion and waste management.
• The oesophagus and stomach are not terminal; they are involved in earlier stages of digestion.
• The colon precedes the rectum but is not the final section of the digestive tract.