Statement A is correct because a Zener diode is specifically designed to be operated in the reverse breakdown region to function as a voltage regulator. Statement B is incorrect because the potential barrier of a p-n junction depends on the semiconductor material used. While it is approximately 0.2 V to 0.3 V for a Germanium diode, it is about 0.7 V for a Silicon diode. Hence, generalizing it as 0.2 V to 0.3 V for any p-n junction is incorrect.