Answer: C. Observations are made in a living mouse.
Explanation:
In-vivo experiment refers to the experimental procedure that occurs in the whole living organism or living cell. It involves the experiment in a natural biological environment. The observations are made in living mouse is the correct option because it involves the whole living organism that is mice.
Variability was seen as imperfection, so natural selection could only eliminate the inferior and imperfect, not giving rise to new things, new species.
