Answer: Commensalism
Explanation: Well you can already eliminate parasitism because that is when an organism leeches off another. Mutualism is when one organism needs to depend on another compared to A where both are benefited.  Then you can eliminate d because competition is when two organism compete with each other for survival not benefiting them both. 
 
        
             
        
        
        
Answer:
Animals engage in characteristic behaviors that increase the odds of reproduction. Animals and plants develop characteristic structures and behaviors to help them survive in their environment and pass on genetic information to their offspring. It is important that the offspring be cared for and protected so they can grow to adulthood and reproduce.
 
        
             
        
        
        
Answer:
The correct answer is "Nitrogen will only become available to other, nearby plants when the nodules or the nitrogen-fixing plant itself dies".
Explanation:
Nitrogen fixing bacteria maintain a symbiotic relationship with plants. Bacteria performs nitrogen fixation providing the plant with ammonia, while bacteria has a safe place and nutrients to prosper. This relationship is very intimate because it occurs at the root hair of the plant at structures called nodules. Therefore, nitrogen will only become available to other, nearby plants when the nodules or the nitrogen-fixing plant itself dies
 
        
             
        
        
        
In a solar system, there is a sun that is in the middle and has planets orbiting around it. The same way, the nucleus is in the middle with electrons orbiting the nucleus. <span />