Answer:
the differnt dna and rna strucures in the mammals cause differen tlooks they have also evolved from being in the wilf most of their lives
Explanation:
 
        
             
        
        
        
A. Earth's magnetic field reverses over time;  the changes show that seafloor spreading  has taken place over time.
Explanation:
The pattern of the magnetic minerals in seafloor ridges are aligned in a repeating pattern because the earth's magnetic field reverses overtime. 
This provides evidence because the changes shows that the sea floor spreading has taken place over time. 
- The concept of sea floor spreading was first suggested by Harry Hess in the early 1960's. 
- Using sophisticated tools, he was able to discover stripe patterns of magnetic minerals in rocks. 
- The earth can be likened to a giant bar magnet
- The geomagnetic field originates from the core where the movement of molten metals induces magnetism. 
- In a fresh cooling magma, the metallic minerals are able to align their domains with the prevailing magnetic field. 
- At some point the magnetic field is normal with a very strong intensity. At other times the intensity is low and it reverses. 
- The minerals keeps track of the changes. 
- This leads to striped pattern that has been used to suggest sea floor spreading. 
learn more: 
Sea floor spreading brainly.com/question/9912731
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<span>The state in which all body systems are functioning smoothly and in equilibrium is homeostasis.</span>