Aqueous acid P and aqueous alkali Q have identical concentrations. $20\,\text{cm}^3$ of P is placed in a conical flask. Q is then added gradually to the flask, and the volume of Q together with the pH is measured. The pH titration curve is shown. Which row identifies P and Q?
- AP = $\text{HCl}$, Q = $\text{NaOH}$
- BP = $\text{H}_2\text{SO}_4$, Q = $\text{NH}_3$
- CP = $\text{HCl}$, Q = $\text{Ba(OH)}_2$
- DP = $\text{CH}_3\text{COOH}$, Q = $\text{Sr(OH)}_2$