A.
Variation in species --> natural selection --> differential reproduction --> heredity --> evolution
B.
Heredity --> variation in species --> differential reproduction --> natural selection --> evolution
C.
Variation in species --> differential reproduction --> heredity --> natural selection --> evolution
Designing Combustion Engines D I think
Answer:
A chronic condition is a human health condition or disease that is persistent or otherwise long-lasting in its effects or a disease that comes with time. The term chronic is often applied when the course of the disease lasts for more than three months.
Explanation:
I think the most involved would be your circular system because since your running fast you need to pump blood. Your muscular system because your moving a lot and your respiratory system because you need more oxygen