To solve this problem, we need to evaluate the correctness of statements (A) and (B).$\\$Statement (A):$\\$A Zener diode is connected in reverse bias, when used as a voltage regulator.$\\$• A Zener diode is specifically designed to operate in the reverse breakdown region.$\\$• When used as a voltage regulator, it is indeed connected in reverse bias.$\\$• This allows the Zener diode to maintain a constant output voltage despite variations in the input voltage or load conditions.$\\$Therefore, statement (A) is correct.$\\$Statement (B):$\\$The potential barrier of a p-n junction lies between 0.1 V to 0.3 V.$\\$• The potential barrier of a typical silicon p-n junction is approximately 0.7 V.$\\$• For germanium p-n junctions, the potential barrier is around 0.3 V.$\\$• The given range of 0.1 V to 0.3 V is not accurate for silicon, which is the most commonly used semiconductor material.$\\$Therefore, statement (B) is incorrect.$\\$Based on the analysis, the correct answer is:$\\$Option 3: (A) is correct and (B) is incorrect.