All the following are necessary parts of a neutralization reaction except a) an acid b) an indicator c) water d) a salt.

The reaction of an acid and a base is called a neutralization reaction because the properties of both the acid and base are diminished or neutralized when they react. A neutralization reaction is a reaction of an acid with a base in aqueous solution to produce water and a salt, as shown by the following equation:

acid + base → salt + water

Therefore the answer is B. an indicator