Hydrochloric acid (HCl) is usually not used in the process of titration because it reacts with the indicator potassium permanganate (KMnO4) that is used in the process. It reacts with KMnO4 solution and gets oxidized which further results in the liberation of chlorine gas according to the following reaction.
2KMnO4+16HCl→2MnCl2+2KCl+8H2O+5Cl2
So, Both A and R are true and R is the correct explanation of A