All of the above are true; none is false
Step-by-step explanation:
Evolution is the phenomena by which an organism gets modified or develops more advanced characters which makes it more fit for the survival in nature.
The first statement is true because evolution refers to the modification of existing characters nothing new develops spontaneously to overcome natural selection. During natural selection organisms that survive gradually surpass the selection pressure. And the evolved character of it gets fixed within the species.
Evolution occurs within the existing mechanisms and structure which find out new ways of surviving in the changing environment.
The genes that control the development are highly conserved and this is the reason we can trace back the similarities with common ancestors. And make a comparitive study of structural anatomy.