PHS defines an investigator as an individual, regardless of tittle or position, who is responsible for the design, conduct or reporting of research funded by the PHS or proposed for such funding. This includes key personnel identified in the grant application, progress report or other report submitted to the funding agency by the Institution. 
        
             
        
        
        
B.) the available food on the islands 
Since these different beaks were adaptions part of their evolution to be able to be more fit to survive with the food available on the island
        
             
        
        
        
Answer:
Chemical Energy!
Explanation:
A Battery is made of chemical energy!