Answer:
The correct answer is C) gene flow
Explanation:
The biological species concept defines what is a species. It says that a species is a group of individuals in a population that interbreed with each other. So there should be gene flow between the members of the population to come under species.
Appearance does not define that two individual are of same species because even different species can look same for example Western meadowlarks and eastern meadowlarks looks identical to each other but they do not interbreed so there is no gene flow between them so they are not same species.
Therefore the primary criteria for determining species boundaries is gene flow.
I don’t know what you are even saying
Phylum, it is the second largest group.
The energy currency of the cells is ATP. This is used for example in photosynthesis where plant cells produce food and oxygen using carbon dioxide and glucose for the consumers. ATP is also used widely in all other cycles to produce different products.