Answer:
C. Viruses 
Explanation:
Viruses lack the properties of living things. They have no energy metabolism, they do not grow, they produce no waste products, and they do not respond to stimuli. They also don't reproduce independently but must replicate by invading living cells.
 
        
                    
             
        
        
        
Answer:
The correct answer is - B. It introduces new alleles into a population.
Explanation:
Gebe flow or migration is the transfer of the genetic material or transfer of genes from one population to another population of the same species. Gene flow is also responsible for the genetic change that leads to evolution.
Gene flow can contribute in various ways such as migration or vertical gene transfer parent to progeny, however, it can lead to evolution directly by introducing new alleles into a population.
 
        
             
        
        
        
 It is kind of a strange question but by the process of elimination, I would go with petrification. 
Its called petrified wood.
hope I Helped
 
        
                    
             
        
        
        
Answer:
I don't know what this says!
Explanation:
 
        
             
        
        
        
First, he should measure how long it takes for the liquid to become clear if X and Y are mixed together. Then, he should measure how long it takes if he also adds substance A to X and Y. He will find out if substance A is a catalyst. hope this helps :)