Air is bled from the pneumatic manifold and conditioned by two

Air is bled from the pneumatic manifold and conditioned by two separate and independent cooling packs. In the above sentence ,"pneumatic manifold" ，“cooling packs”means

A.配平空气管道，冷却组件;

B.侧壁竖管，空调组件;

C.顶部分配管，冷却组件;

D.气源总管，冷却组件;

正确答案是D