Answer:
The answer is number two extinction happened, this was the time dinosaurs went extinct ebcause lack of sun because oh how much dirt was blown into the earth atmosphere becuase of the asteriod, third option is talking about big bang theroy so that dosnt apply!
Explanation:
 
        
             
        
        
        
AT, GC
Explanation:
Adenine (A) pairs with Thymine (T).
Guanine (G) pairs with Cytosine (C).
A - T
C - G
T - A 
T - A
G - C
C - G
hope this helps you! 
 
        
             
        
        
        
Answer:
the outermost layer of Earth's lithosphere
Explanation:
the outermost layer of Earth's lithosphere that makes up the planet's continents and continental shelves and is formed near subduction zones at plate boundaries between continental and oceanic tectonic plates. The continental crust forms nearly all of Earth's land surface.
 
        
             
        
        
        
Answer: For decreased chances of rejection 
Explanation: 
The three higly polymorphic MHC 1 genes in human beings are HLA-A, HLA-B and HLA-C.
These determine the compatibility of the organ or tissue in the recipient's body each by the help of many alleles that segregates in a population.
There are very less chances that a random chosen donor will match the a recipient six allele genotype.
This is the reason parent  may be the best donor for organ transplantation or tissue transplantation.
 
        
             
        
        
        
Answer:
C
Explanation:
(Humans) body cells and viruses both contain RNA and DNA. So both have this similarity.