The greater the electronegativity difference, the moreionic<span> the </span>bond<span> is. </span>Bonds<span> that are partly </span>ionic<span> are called</span>polar<span> covalent </span>bonds<span>. </span>Nonpolar<span> covalent </span>bonds<span>, with equal sharing of the </span>bond<span> electrons, arise when the electronegativities of the two atoms are equal</span>
        
             
        
        
        
The correct answer of the given question above would be option D. The option that did not occur during the Cenozoic era is the formation of the ozone layer. The ozone layer has long been there before any era since it is part of the earth's atmosphere. Hope this answer helps. 
        
                    
             
        
        
        
<span>Sedimentation - uses solutions of lower specific gravity than the organisms, which concentrated in the sediment. This technique is recommended for general diagnostic laboratories because it is easy to perform and less prone to technical errors.
Flotation - this technique uses solutions of higher specific gravity than the parasitic organisms so the organisms float and the debris sinks producing a cleaner material while the disadvantage is that walls of cysts and eggs collapse that may blocking its identification.<span>
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Individuals with these mutations typically have familial hypercholesterolemia.
These genes provide information for the formation of the low-density lipoprotein receptor, a receptor that binds to low-density lipoproteins (LDLs). LDLs carry the cholesterol in the blood and regulate the amount of cholesterol in the circulation. Mutations to these genes either reduce the number of receptors or cause several disruptions to their function. This results in high blood cholesterol levels and in a higher risk for heart disease.