Answer:
The correct answer is ''high survival rates of offspring and the cost of parental care''
Explanation:
Natural selection is the differential reproduction of some genetic variants with respect to others. Natural selection favors individuals who maximize their total reproductive success throughout life, that is, it favors certain phenotypes or variants are associated with greater offspring and / or greater survival, that also means that selection will favor those who stop spending on a particular breed at the right time to invest in another, that is, the amount of energy invested in each of them. This same natural selection also favors those genes that make it effective when the body that carries them is in development to extract all possible parental investment from their parents.
 
        
             
        
        
        
Answser 
it migth be B i am not sure
 
        
             
        
        
        
Answer: Mutualism
Explanation: The definition of mutualism states " interaction between two or more species where each species has a benefit". The bird is getting food from the insects and the horse is getting the insects removed. Both are benefited. 
 
        
             
        
        
        
Answer:
The unified cell theory states that: all living things are composed of one or more cells; the cell is the basic unit of life; and new cells arise from existing cells. Rudolf Virchow later made important contributions to this theory.
Explanation: