Which of these most likely represents a chemical change?
a. water boiling.
b. sugars digested by saliva.
c. mud drying to dirt.
d. ice cream melting.

Option (b) is the correct answer.

Explanation:

An enzyme called salivary amylase helps in the breakdown of sugar into small particles. This enzyme affects the sugar for a small period of time in the mouth.

Once, salivary amylase reaches the stomach it becomes inactive because of the acid present in stomach. Further, this acid breaks the sugar molecules and these molecules are sent to the intestine for further reaction.

Thus, we can conclude that sugars digested by saliva is a chemical change.