Answer:
600 kcal
Explanation:
In an ecosystem, energy is transferred from one organism in a trophic level to another organism in another trophic level. Organisms called PRODUCERS are capable of deriving energy from the sun. However, when fed upon by PRIMARY CONSUMERS, only about 10% of the energy is transferred to them because most of the energy (90%) is lost as heat. 
Hence, in this case where the producers had 6,000 kcal of energy, 10% i.e. 10/100 of 6000 = 600 kcal of energy will be transferred to the primary consumers.
 
        
             
        
        
        
The answer would have to be D
        
             
        
        
        
I believe it should match as the following...
sight in whales -----> eyeballs in cavefish
balance in monkeys -----> tailbone in humans
attachment point for limbs in frogs -----> pelvis bone in whales
        
                    
             
        
        
        
The second one because they can indicate infection and sickness
        
                    
             
        
        
        
Nitrogen is returned to the atmosphere during the nitrogen cycle in a process referred to as denitrification.
<h3>What is denitrification?</h3>
It is a process whereby nitrogen becomes mineralized from nitrogenous compounds. In other words, it is the reduction of nitrates to produce elemental nitrogen which is returned to the atmosphere.
Denitrification is a microorganisms-driven process. The nitrates are made to pass through a series of reactions with intermediate products before finally leading to the production of elemental nitrogen.
More on the denitrification process can be found here: brainly.com/question/13624886
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