Answer:
The picture is just a black screen so I can’t see the question
The Major function of the respiratory system is to exchange oxygen and carbon dioxide. Inhaled oxygen enters the lungs and reaches the alveoli, the layers of the cells lining the alveoli and the surrounding capillaries are each only one cell thick and are in very close contact with each other, the barrier between air and blood averages about 1 micron in thickness. Oxygen diffuses quickly through the air-blood barrier into the blood in the capillaries. Similarly, carbon dioxide passes from the blood into the alveoli and is then exhaled.
A catalyst increase a chemical reaction, therefore making the answer B. Promotes a chemical reaction.
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During the lunar month, the Moon goes through all its phases. You can see the phases drawn in the image below. Just like the Earth, half of the Moon is lit by the Sun while the other half is in darkness. The phases we see result from the angle the Moon makes with the Sun as viewed from Earth.
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