The correct answer is A) piston 'F" moving upward to shut the makeup steam valve "B" and open the exhaust valve "E". The gland seal regulator is designed to maintain a constant pressure around the piston rod by allowing makeup steam to enter when the pressure drops, and exhausting steam when the pressure increases. An increase in gland seal pressure will cause piston "F" to move upward, which will shut the makeup steam valve "B" and open the exhaust valve "E", allowing the excess pressure to be released. This is the correct operating mechanism for the gland seal regulator under increased pressure conditions. The other answer choices do not accurately describe the response of the regulator to an increase in gland seal pressure.