Protons and neutrons. But since the protons outweigh the neutrons. so your answer is d
The disease is mainly caused by a lack of a slippery substance in the lungs called surfactant. This substance helps the lungs fill with air and keeps the air sacs from deflating. Surfactant is present when the lungs are fully developed.
https://medlineplus.gov/ency/article/001563.htm
Answer:
a vestigial structure
Explanation:
Vestigial structures are a rudimentary (or even functionless) version of a body part, but they have important functions in a closely correlated or evolutionarily close species, an example of which is the presence of eyes in fish of the genus Astyanax. The existence of these vestigial structures is strong evidence that evolution occurs in organisms, since this structure, today without much apparent function, may in the past have been extremely important to the ancestors of that species.
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Digestion occurs when food is moved through the digestive system. It begins in the mouth and ends in the small intestine. The final products of digestion are absorbed from the digestive tract, primarily in the small intestine.
