Which of the following is an example of a decomposition reaction?
a. photosynthesis
b. digestion
c. polymerization
d. exchange of ions between two compounds

The answer is (b) digestion.
A decomposition reaction is a process in which a single compound breaks into two or multiple elements or compounds. A best example is digestion where a large insoluble food molecules breakdowns into small water-soluble molecules so that they can be absorbed into the watery blood plasma.

Answer///air resistance,drag;