In aqueous solution, the pH of a substance is a measure of its:

• A. total concentration of dissolved ions (ionic strength)
• B. hydroxide ion concentration, $-\log \left({\left[}_{{\mathrm{OH}}^{-}}\right)$
• C. hydrogen ion concentration, $-\log \left({\left[}_{H^{+}}\right)$
• D. temperature of the solution

Answer: (C)