A. Because saturated fatty acids are the ones with no double bonds
        
             
        
        
        
Since fire is a chemical reaction, and oxygen is needed for that reaction, having a fire in a cave is a sure sign of the presence of oxygen.
        
             
        
        
        
The answer is written on hand, and sorry for that because I am on driving having no resources except hand and ball point to solve your problem. Sorry for that however answer is given.
 
        
        
        
Answer:
D. Crossing<em> over occurs after replication and only sister chromatids exchange gene segments to make new combinations of genes.</em>