Starting at least level up to the largest as organized by ecologists, see the chart below.
Answer: option C) species -> community -> biosphereD
Explanation:
Species refers to closely related organisms (plant or animal). When different species of organisms live together in a habitat where they feed on one another and become codependent on one another, a COMMUNITY has been formed. 
A BIOSPHERE, however is composed of many ecosystems i.e different species of plants, animals and microorganisms relating with their environment. Thus, a biosphere = Communities + environment 
 
        
             
        
        
        
Blood needs to flow faster around the body in order to supply the muscles with oxygen for respiration
        
             
        
        
        
Answer:
Septic tanks and oxidation ponds
Explanation:
These system of wastewater treatment and disposal are not too feasible in large municipalities because of the presence of sewer system that has been made available by government, in order to mitigate the possibilities of transmitting enteric diseases that are very harmful to human health. 
 
        
             
        
        
        
Answer:
The chance of a normal couple having a child with down syndrome is 1 to 600 births.
Explanation:
Down syndrome is a genetic flaw that occurs when the fetus is being formed.
A human cell considered normal has 46 chromosomes, divided into 23 pairs. For some unknown reason, an error may occur at the beginning of embryonic development and an extra chromosome is created, which binds to par 21. The result is cells with 47 chromosomes. This causes the said syndrome.
It is important to know that this failure happens at random. It is nobody's responsibility. It has not been proven to date that lifestyle, actions during pregnancy, smoking, drinking, medicines, environmental factors or kinship between the couple can influence this occurrence. She is not contagious either. The likelihood of a normal couple having a child with the syndrome is approximately 1 to 600 births.
 
        
             
        
        
        
Answer:
A decomposer is found at the end of a food chain.