An Alert Patient Receiving Intermittent Mandatory Ventilation at a Rate

An alert patient receiving intermittent mandatory ventilation at a rate of 8/min and V_T of 600 ml has stable vital signs and satisfactory blood gases on an FiO₂ of 0.45. What would you do to initiate weaning for this patient?

A) Lengthen the automatic sigh interval.
B) Decrease the mandatory rate to 5 to 6/min.
C) Increase FiO₂ to 60%.
D) Decrease the V_T to 500 ml.