Answer:
Option B, Digestion
Step-by-step explanation:
As the name suggest in a decomposition reaction a bigger chemical substance is broken down into simpler chemical substances.
For instance, during the process of digestion carbohydrates (CHO compounds) such as starch decomposes into glucose. Like wise protein decomposes into amino acids and complex fat molecule decomposes into simpler fat molecules. Thus, digestion is a decomposition reaction.
Thus, option b, digestion is the correct answer.