el carbon es bueno para el atmosphere
Complex organisms need cells that can perform many different functions. they need to be supported on a cellular level. Without specialized cells you they won't be able to perform different functions.
I believe the correct answer among the choices listed above is option A. Parasitism is the kind of interaction that is shown here. Parasitism is a kind of relationship where one feed off the other. Fleas here are referred to as the parasite and the dog is the host.
This is the gene cycle and if their mother has different gene then that will happen.