Physical change only change the appearances of a substance, not it’s chemical composition. Chemical changes cause an entirely new substance with new chemical formula.
There are many types of natural selection like direct selection, disruptive selection and stabilizing selection.
The situation given is that a population of mice lives in a city. The largest mice tend to be killed by predators and the smallest mice cannot compete for food.
The type of selection here is stabilizing selection. It is a type of natural selection in which there is decrease in genetic diversity as the population stabilizes.
I think is a) dilates the bronchi
While moving in between areas of land glaciers erode the land around them, this eroded land leads to weathering from the sand and rocks eroded. Example The Grand Canyon
