Human evolution known to be a process in which species adapt to certain conditions of life, and in the battle of life and death, they are forced to become stronger in order to survive in the world. Diseases have always been present during the evolution, acting themselves as a natural selector-the weaker organisms get sick and die.
        
             
        
        
        
It's B
Explanation:
Because the fossil record shows how organisms have evoluate from relatively simple organisms to more complex organisms
 
        
                    
             
        
        
        
Answer:
The correct answer will be option-A.
Explanation:
The females carry two X-chromosomes in their cells but one of these X-chromosome gets permanently inactivated during embryonic development.
The X-inactivation is known as lyonization which ensures that only one functional X-chromosome should be present like in males.  This process is a random process and therefore a female can have both the functional X-chromosomes and males can also have a functional X-chromosome.
Thus, option-A is the correct answer.
 
        
             
        
        
        
Here is a diagram I found online if it helps!