1) C
A population has to be isolated for speciation
2) D
Different species are incapable of reproducing with one another
3) D
When a population is contained, the recessive alleles can become dominant within the population
        
                    
             
        
        
        
not gonna lie, this is more of an answer you'd have to answer yourself. It seems like an easy question just think about it. If you're a scientist in a drought, think about places where youd be able to get water. Some plants produce water as well. Soil holds water, Even under normal climatic conditions, about 90 per cent of the precipitation is said to be released back into the atmosphere.
 
        
             
        
        
        
Can you please define you question?
        
             
        
        
        
Answer: Myelin 
Explanation:
The speed of the neurotransmission increases as we grow. The behavior of the teenager is quite different from the behavior of the adolescents. 
They are more active, heroic and wants to take risk. This is because their brains are not completely developed till they reach the age of 25.
As they grow and reach the late 20s the white mater in the brain increases as the frontal lobe is the last part of the brain development.
Due to the development of the myelin in the frontal lobe the transmission of the signal increases at adolescence.
 
 
        
                    
             
        
        
        
testes → sperm duct → glands → urethra → penis
You're welcome. Have a great day!
:)