Answer:
The answer is A. a tissue
Explanation:
Tissues are groups of similar cells that have a common function. An organ is a structure that is composed of at least two or more tissue types and performs a specific set of functions for the body.
Usually microorganisms help keep the nutrients in the soil cycling allowing for nutrients to be distributed all over. But they do what they can unless the disease is damaging to the soil itself therefore damaging the microorganisms working to keep the plant functioning.
The coronary arteries supply oxygen to The heart muscle
It has more similarity to fossils in layer A than layer D.