Answer:
DNA was discovered in 1869 by Swiss researcher Friedrich Miescher, who was originally trying to study the composition of lymphoid cells (white blood cells). Instead, he isolated a new molecule he called nuclein (DNA with associated proteins) from a cell nucleus.
Explanation:
 
        
             
        
        
        
So you don’t tear any tissue and so they get more elastic.
        
             
        
        
        
Th answer is D its the best answer that fits the question . 
        
             
        
        
        
Nosocomial infection-acquired in hospital or health card facility
        
             
        
        
        
Answer: The lock-and-key mechanism is usually associated with the complementary shapes of an enzyme with a single substrate wherein the lock that is being referred to is the enzyme and the substrate is the key. One right sized substrate (key) fits into the active site (key hole) of the enzyme (lock).