For gas exchange to be efficient, the respiratory membrane must be
a. 0.5 to 1 micrometer thick
b. between 5 and 6 micrometers thick
c. at least 3 micrometers thick
d. the thickness of the respiratory membrane is not important in the efficiency of gas exchange.

A- 0.5 to 1 micrometer thick

Explanation:

During gaseous exchange, the oxygen moves through the respiratory membrane into the blood and the carbon dioxide travels through the respiratory membrane out of the blood. The thickness of the respiratory membrane should be about 0.6 micrometers. A thicker membrane would result in slower and decreased gaseous exchange.

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