Which regions of the vascular bed is the actual site of gas exchange with surrounding tissue?

Capillaries

Explanation:

Capillaries are thin cells and help to gas exchange with surrounding tissue.They are little to such an extent that red platelets need to course through them a single record. In the event that all the Capillaries in the human body were arranged in a single record, the line would extend more than 100,000 miles. Encompassing this layer of cells is something many refer to as the cellar film, a layer of protein encompassing the narrow. Carbon dioxide (from deoxygenated blood) thus spills out of the Capillaries once more into alveoli to be breathed out into the earth.Hence, the "capillaries" is the right answer.

Gas Exchange Process in Body

Explanation:

The convey of oxygen from the lungs to the circulatory system, and elimination of carbon dioxide  from the circulation system to the lungs.it is known as gas exchange process.The lungs between the alveoli and a system of little veins called vessels, which are situated in the dividers of the alveoli.  The essential capacity of the lungs including the exchange of oxygen from breathed in air into the blood and the exchange of carbon dioxide from the blood into the breathed out air.  Gas exchange is significant on the grounds that it gives oxygen to the cells of living life forms with the goal that they can get vitality from natural atoms.  Three principle factors that influence gas exchange in the two animals  and plants:  Surface territory of the film. The bigger the surface region of the layer the higher the pace of gas exchange that happens.Fixation inclination.  Thickness of the film.

Ithink the answer is d.