Answer is: B. acidic.
pH (potential of hydrogen) is a numeric scale used to specify the acidity or basicity of an aqueous solution:
When pH is less than seven (pH<7), solution is acidic.
When is equal seven (pH = 7), solution is neutral.
When pH is greater than seven (pH > 7), solution is basic.
For example, hydrochloric acid( HCl) is acidic, it ionizes in water solution and gives the hydrogen cations and chloride anions (Cl⁻):
HCl(aq) → Cl⁻(aq) + H⁺(aq).
