The statement "animals that do not maintain a constant body temperature" is correct, they are the organisms that do not use NADH to feed electrons into mitochondrial electron transport chains.
Animals that do not keep a constant body temperature do not need NADH and do not consume NADH during respiration, as NADH is needed for maintaining a constant body temperature and is thus required by the organism.
The second method uses the respiration process used by bacteria and archaea, which uses NADH. The eukaryotic algae in the third option employ NADH in respiration since eukaryotes often do so. In the fourth option, animals must use NADH for respiration in order to keep their body temperatures constant.
If NADH is not available, oxidative phosphorylation reactions uncouple, which maintains the body temperature. This type of reaction is seen in animals that are hibernating as well as in newborn animals and people.
Here is another question with an answer similar to this about mitochondrial electron transport chains: https://brainly.com/question/15318900
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