The given figure shows the digestive system of humans. What happens in the part marked as X ?

Options

A. Excess water is absorbed into blood stream, undigested wastes are converted to faeces.
B. Alkali neutralises acid and helps breakdown of fats, small food molecules are absorbed into bloodstream.
C. Food is mechanically broken into small pieces and enzymes from saliva are added.
D. Food is mixed with gastric juices, hydrochloric acid kills most harmful bacteria and creates pH required to breakdown proteins.

Answer

D

Explanation

In the given figure, part marked as .X. is stomach. Here the food is churned and mixed with gastric juice. Gastric juice contains hydrochloric acid and digestive enzymes. Hydrochloric acid maintains a strongly acidic pH in the stomach. It kills bacteria and other harmful organisms that may be present along with food. The digestive enzymes of stomach (mostly protein digesting) are activated in the acidic medium created here by HCl and partial digestion of food (proteins and fats) takes place.