The structure that formulates the displayed blood-air barrier would be:
A). structures A and B
Human Lung
The human lung is a complex organ in the human body that functions to assist in the process of respiration by supplying oxygen to the flow of blood in the body.
In the given image, structures A, as well as, B have been causing the barrier of blood in the body.
This is because the barrier is made of epithelium alveolar, along with endothelium capillary.
Thus, option A is the correct answer.
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