Answer:
Genetic drift 
Explanation:
Genetic drift is defined as the random change in allelic frequencies from one generation to the other.
Genetic drift is an evolutionary mechanism in which the allelic frequencies in a population change through many generations. Its effects are harder in a small-sized population, meaning that this effect is inversely proportional to the population size. Genetic drift results in some alleles loss, even those that are beneficial for the population, and the fixation of some other alleles by an increase in their frequencies. The final consequence is to <u>randomly</u> fixate one of the alleles. Low-frequency alleles are the most likely to be lost. Genetic drift results in a loss of genetic variability within a population.  
Genetic drift has important effects on a population when this last one reduces its size dramatically because of a disaster -bottleneck effect- or because of a population split -founder effect-.
 
        
             
        
        
        
Answer:
The correct answer will be option-D.
Explanation:
In the given question doctor used the scientific method to understand and explain the natural phenomenon.
The scientific method involves various steps like making an observation followed by background research, predicting a hypothesis and performing tests to test the hypothesis. These steps have been performed by the doctor.
After these steps the doctor will analyse the result and reach to the conclusion. This would be followed by publishing the results in a scientific journal where it would be reviewed by the fellow scientists.
Therefore, the next step will be publishing the result and thus option-D is the correct answer.
 
        
                    
             
        
        
        
The head at the top, the tail is just for getting to the egg
        
             
        
        
        
Answer:
B
Explanation:
Environmental factors don't determine all of your genetics traits but they do influence them.
 
        
             
        
        
        
If a substitution changes the amino acid to a “stop,” it's called a NONSENSE mutation. frameshift, missense, silent or nonsense (hint: deletion or insertion will always be frameshift). Sickel cell anemia is the result of a type of mutation in the gene that codes for part of the hemoglobin molecule.