Which one of the best illustrates a qualitative (rather than quanitative) change in development?

Can you tell the size of a woman's coxal bone by observation?

Whic disease reduces bone density and causes the bones to become brittle

Why is it so important to have a lifetime commitment to training? a-it takes your entire life to become fit b-it keeps you from becoming bored c-you will lose strength and endurance once you stop exercising d-it increases your motivation in life