Continuous spectrum and line spectrum are two types of spectra; their main difference is that continuous spectrum contains no gaps whereas line spectrum contains many gaps.
        
             
        
        
        
The correct answer is high temperature solids
        
                    
             
        
        
        
Answer:
A) solute - NaCl, solvent - water
B) solute - O2 and other gases, solvent - N2
C) solute - ethanol, solvent - water
D) solute - tin, solvent - copper
Explanation:
Solute(s) is/are the minor component(s) in a solution, dissolved in the solvent.
Solvent is the component of a solution that is present in the greatest amount. It is the substance in which the solute is dissolved. 
If both solute and solvent exist in equal quantities (such as in a 50% ethanol, 50% water solution), the concepts of "solute" and "solvent" become less relevant, but the substance that is more often used as a solvent is normally designated as the solvent (in this example, water).
 
        
             
        
        
        
An "adaptation."  It's the natural way that birds of flight adapt to their needs or environment which makes them more efficient.  :)