Answer:
A mutation in the DNA sequence of the gene for brown fur  
Explanation:
The mutations are capable of changing the encoded protein product, in this case the gene that encodes for the fur color pigment. This mutation may have occurred during mitosis or meiosis divisions. 
If it is a spontaneous mutation that occurred in the germinal line (meiosis) and confers an adaptive advantage, it will increase their frequency in the population.
 
        
             
        
        
        
The right answer is Watson and Crick.
The famous science journal "Nature" published an article of two pages, accompanied by one figure, titled "A Structure for Deoxyribose Nucleic Acid". Its authors are James Dewey Watson (24) and Francis Crick (36).
They synthesized the work of their scientific colleagues and were able to explain with a remarkable art of deduction how the DNA molecule contained in the cells of all living beings was duplicated.
 
        
                    
             
        
        
        
The trp repressor blocks transcription of the trp operon (B) when the repressor binds to tryptophan.
trp operon or the tryptophan operon codes enzymes for the amino acid tryptophan. The operon is on when the tryptophan is low in amount whereas the operon is off when the tryptophan is low in amount. The operon is an assimilation of five genes.
Repressor is a small protein that is supposed to prevent the synthesis of proteins. It does so binding to the operator gene. Therefore, presence or absence of repressor is a determining factor for an operon to be on or off. 
To know more about trp operon, here
brainly.com/question/28239403
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Other population of the primary consumer or to what the consmers eat will expand in number