B) The atria only recieve blood and the Ventricles have to pump the blood
        
             
        
        
        
The abdominal cavity is lined by peritoneum. It is a membrane that covers the inner layer of the cavity and also the organs inside. The membrane on the inner wall is parietal Thperitonium and the membrane that lines the organ is called visceral peritoneum.  This helps in fixation and support of abdominal organs.
        
             
        
        
        
There are four principles at work in evolution—variation, inheritance, selection and time. The theory of evolution by natural selection, first formulated in Darwin's book "On the Origin of Species" in 1859, is the process by which organisms change over time as a result of changes in heritable physical or behavioral traits.