If the mass of the pendulum increases, the initial potential energy will increase.
Potential energy in a pendulum is given by the formula \( PE = mgh \), where \( m \) is the mass, \( g \) is the acceleration due to gravity, and \( h \) is the height above the reference point. Therefore, with an increase in mass, the initial potential energy increases as long as the height (\( h \)) remains the same.
So, the correct response is: The initial potential energy will increase.