Nucleic acids is what it would be known as
        
             
        
        
        
<span>The correct answer is d. the idea that T. rex held its tail aloft was supported by the studies of many scientists. This is how science works, things are discovered by having members of the scientific community do experiments and come to the same conclusion. Many of them confirmed this theory and a concensus was established.</span>
        
                    
             
        
        
        
Star brightness is defined by either <span>D. apparent magnitude - when we measure it from Earth (that is how bright it is from Earth) - this is the closest to "basic observation" and the best answer
or by absolute magnitute - how bright it would be at a certain distance (this allows to compare the brightness). 
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