Answer:
The small intestine.
Step-by-step explanation:
Digestion may be defined as the process of breakdown of large food molecule into simpler substances with the help of enzymes and digestive juices. Digestive system includes the alimentary canal and its associated glands.
The process of complete digestion and maximum absorption occur in the small intestine. Small intestine contains numerous finger like structures called villi, these villi increases the surface area that helps in the food absorption.
Thus, the correct answer is option (4).