What is the alveolar-capillary membrane? the layer of cells through which gases are exchanged
the layer of cilia that traps debris from entering lungs
the pathway to the lungs from the trachea
a pulmonary artery that exchanges gases

What link in the chain of transmission is described in the paragraph? sarah has been eating and sleeping poorly. she was just diagnosed with pneumonia. tests showed the illness was caused by streptococcus pneumoniae. in the chain of transmission, sarah is the (blank) , and streptococcus pneumonia is the (blank).