Answer: unfavourable ph condition for the pepsin
Explanation: during digestion, enzymes are needed to aid the process.digestive enzymes are biological catalyst that breakdown large food particles into digestible form .
As biological catalyst, enzymes require an optimum temperature and pH condition.outside this temperature or pH,the enzyme is denatured.
In the stomach, hydrochloric acid is required to convert pepsinogen into it's active form,pepsin.the acid also creates an optimum low pH that pepsin needs to function.
As the food moves to the small intestine,the pH is alkaline and is unfavourable for pepsin to function.