ANS:C - ≥ diameter

The discharge through an internal mouthpiece is more when its length is greater than the diameter of the mouthpiece. For an internal mouthpiece, the length of the mouthpiece affects the flow rate. When the length of the internal mouthpiece is greater than the diameter, it allows for smoother flow conditions and reduces losses due to friction, resulting in a higher discharge. Therefore, the correct statement is: the discharge through an internal mouthpiece is more if its length is greater than the diameter.