Answer: Option (C) is the correct answer.
Step-by-step explanation:
It is given that when an acid and a base form a salt and water.
For example,

Therefore, in this type of reactions there is exchange of ions between the two compounds hence, it is known as double-displacement reaction.
Thus, we can conclude that out of the given options the term an acid and a base form a salt and water describes an acid-base reaction.