The answer is “it is the gap between neurons” and “it ensures that information travels in one direction only.”
        
             
        
        
        
Birds and butterflies don't have a common ancestor because one is a member of a insect and the other is well a bird. They both have different body structure. One has bones and the other has an exoskeleton. hope this helps  
 
        
             
        
        
        
Fish poop.
Tropical white beaches get their pearly white color from the excrement of fish far off of the coast which eat coral and other things that reside on the ocean floor. When they eat they swallow some sand into their mouths as well, and process it with the food they just ate. Their stomachs can't really digest the sand, tiny minute rocks essentially, and thus turn their color white. Or the rock forming the sand can be naturally pigmented a whitish tone as well.
        
             
        
        
        
B.Sometimes true,As you sometimes to need to learn on the alternative provided in getting a solution that is factual