Answer: population density
Explanation:
<span>d. All of the above
These behaviors;
Spreading wings
Flattening feathers
panting
are all evolutionary process to maintain body temperature. Birds are warm-blooded animals. Also known as </span><span>homeotherms, which is defined as having the constant body temperature. This is a vital function for the survival of the specie.
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<span>c. are hollow
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The bones of most birds are hollow in order for the weight of the birds to be light for them to fly.
The answer here is ATP.
ATP is used in the first step of glycolysis to convert glucose into glucose-6-phosphate (that's where the phosphate comes from).
<span>Earth went through a period of hot and also dry conditions and a wide spread drought.These conditions favored reptiles and therefore causing them to evolve during those conditions. Hope this helps :)</span>