Answer: Option (a) is the correct answer.
Explanation:
Acids are the species that contains number of hydrogen ions.
Foe example, HCl is an acid.
Whereas bases are the species that contain hydroxide ions.
For example, NaOH is a base.
Therefore, in order to check whether an unknown chemical is an acid we can test the hydrogen ion concentration in the sample.
As this can lead to detection of the sample.