Answer:
If I am correct it is when the weaker individuals or mutated individuals are killed of by other predators or by nature. Because they cannot survive this is natural selection because they are killed of by nature. Then if they are weak their species will go extinct, thus they are naturally selected to die and only the strong species remain.
For example using the tank can determine if one thing is pure gold and another thing has a little bit of gold but also has brass and you want to know about but the shapes need to be same the size for both objects
