Answer:
A. Increasing the food supply 
 
        
             
        
        
        
Alcoholic fermentation; carbon dioxide. Alcoholic fermentation produces alcohol and carbon dioxide in bread. The alcohol evaporates during the baking process.
 
        
             
        
        
        
Answer 1,2,3,4:
As both are heterozygous therefore Male genotype will be (BbEe) and the genotype of female will be (BbEe). While both will have the phenotype black.
Parent Genotype
Male X Female
BbEe X BbEe
 Possible gametes from Parents
Male X Female
BbEe X BbEe
(BE) (Be) (bE) (be) X (BE) (Be) (bE) (be)
...
F1  generation will have following genetypic ratio
Black Labrador = 9  = B_E_
Brown Labrador = 3  = bbE_ 
Yellow Labrador = 3  = B_ee
Yellow Labrador = 1  = bbee
Furthermore, the phenotypic ration will be
Black Labrador = 9
Brown Labrador = 3
Yellow Labrador = 4
 
        
             
        
        
        
Alfred Marshal was one of the most influential economists of his time and the author of the Principles of Economics book which was the principal economic textbook in England for long years. During his economic theory development, he borrowed a concept from the marginalists which is the theory of demand and the collective result of buyers who yearns services and products or the concept of scarcity.