Answer:
This experiment proved that DNA replicated semiconservatively; half the original polynucleotide is conserved in each of the two copies
Explanation:
Semi-conservative mode of replication means that the two strands of DNA unwind from each other, and each of themacts as a template for synthesis of a new, complementary strand. As a result, two formed DNA moleculesc ontain one original strand and one new strand.
Meselson and Stahl experiment showed this model by labeling the DNA of bacteria across generations using isotopes of nitrogen ( patterns of DNA labeling showed the mode of replication).
 
        
                    
             
        
        
        
I think the correct answer from the choices listed above is the third option. The barrel of a gun is also known as bore. The barrel is the metal tube which the bullet is fired and the bore is the inside of the barrel. It is the one closest to the barrel so it must be the answer.
        
                    
             
        
        
        
Enzymes (Catalysts) lower the required activation energy, allowing the reaction to happen more quickly.