When Lying Down,a Subject's Respiratory Rate Is 12 Breaths Per

When lying down,a subject's respiratory rate is 12 breaths per minute,his anatomical dead space is 150 ml,and his minute ventilation is 7 L/min.Which of these is closest to his alveolar ventilation in liters per minute?

A) 6.0
B) 5.2
C) 4.2
D) 3.0
E) 0.583