Answer:
Natural selection
Explanation:
The principle of natural selection was survival for the' fittest'.The survival of an organism depends the variation or development of traits that will enable it and reproduction. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generation
The new born girl had an undesirable trait (no teeth) that lead to difficulties in eating. She could not survive without food hence died due to starvation thus ,the trait was eliminated since she did not reproduce.