Answer: A.) The nitrogen cycle recycles nitrogen through an ecosystem, making it available to all organisms.
Explanation: Nitrogen is an essential nutrient for plants and a significant component of proteins, which all animals need to grow, reproduce and survive. The nitrogen cycle converts nitrogen into compounds that plants and animals can use.
 
        
             
        
        
        
Dinoflagellates is the algal divison.
        
             
        
        
        
The correct answer is C. New experiments can affect previous scientific explanations. 
Explanation: An experiment is a way of checking a phenomenon under specific conditions to analyze its effects or to verify a hypothesis. An example of this is the statement because before the seventies it was believed that new neurons could not be generated in an adult brain, however, after conducting an experiment on songbirds it was found that it was possible. Therefore, it confirms that new experiments can affect previous scientific explanations because new experiments can test hypotheses that modify previous explanations. So the correct answer is C. New experiments can affect previous scientific explanations.
 
        
                    
             
        
        
        
I Think that's the equator
        
                    
             
        
        
        
Answer:
B. Energy needs 
Explanation:
As an individual ages there is a characteristic natural loss of muscle mass that occurs and increases as they move into older years. Changes in lifestyle, such as transition from employment to retirement, also account for a decrease in energy needs. This is because there is less amount of work done during retirement than when an individual is actively working.
The less amount of work is the reason why there is also a corresponding decrease in the energy needs.