While practicing steep turns, you establish a 45-degree bank to the left with appropriate power and back pressure to maintain altitude. Moments later, the bank angle begins to increase toward 50 degrees. The most appropriate corrective action is to

While performing a steep turn to the left at 45 degrees of bank, the airplane begins to roll further into the turn beyond the desired bank angle despite holding the ailerons neutral. What is the primary aerodynamic cause of this overbanking tendency, and what is the appropriate corrective action?