<span>Cellular respiration Is the correct answer</span><span />
Answer:
A scientific theory refers to the possible explanation of the natural event. It can be tested repeatedly and can be verified by anyone with the help of predefined sets of protocols and scientific experimentation.
Similarly, Darwin proposed the idea of natural selection as the mechanism of evolution.
Various experiments in labs, as well as observations made under natural conditions, proved that natural selection plays a major role in the evolution.
Examples may include industrial melanism of peppered moths, long neck of Giraffe, different shapes and sizes of beaks of Darwin finches et cetera.
This is why natural selection is considered a theory now.
