Answer: Option (a) is the correct answer.
Step-by-step explanation:
pH is the measure of concentration of hydrogen ions present in a solution.
Mathematically, pH = -
![(1)/([H^(+)])](https://img.qammunity.org/2018/formulas/chemistry/high-school/m2nbvy3rh65enlte122jju408j9ci741mz.png)
where
= concentration of hydrogen ions
More is the concentration of hydrogen ions present in a solution, less will be the value of pH. Hence, more will be the acidic nature of the solution.
Thus, we can conclude that pH is a measure of hydrogen ion concentration.