Adaptation through natural selection
        
                    
             
        
        
        
Endocrine signaling is hormone based signaling that travels through the blood stream. Many of the sensors and integrating sensors of the endocrine system are located in the brain. The brain barrier contributes to endocrine signalling, such that the brain barrier does not factor in with endocrine signalling. The answer is A
        
                    
             
        
        
        
Correct question:  A fast swimming strong body fish such as a <u>salmon</u> which is adapted to clear fast and strong water current would most likely be found in which aquatic zone? Options in the attached file
Answer:
Source of a river zone
Explanation:
The fishes body is directly correlated with their environment and the pressures they receive from it. Those animals that are used to living in clear waters, with fast currents must be very strong, must have a hydrodynamic torpedo-like body and big and strong caudal fin to propel against the currents. These animals are used to living in water masses such as the source of a river zone. 
Rivers belong to lotic environments, characterized by constant moving water.
- Profundal zone: Sunlight can not reach this zone, so there are no plants. The Water movement is very limited, and in most cases, water is not clear.
- Littoral zone: Is the transition zone, near the shore, where the light easily reaches the bottom. Usually, there is plenty of vegetation fixated to the bottom. 
- Wetland zone: In general these are calm water, very rich in diversity, and a proper breeding area for a wide variety of fish. 
- Source of a River zone: Rivers flow from higher to lower areas. They originate at the top of the mountains and fastly descend to finally end in a lake or in the sea. 
Some species of salmons characterize by living in the sea during sexual maturity, but whenever they need to breed, they go back to the area where they were born. This is in sweet water. They swim in the river until they reach the place where they are going to oviposit. In order to do this, they need to swim against the current. Many times, females die trying to reach this special place. 
 
        
             
        
        
        
Answer:
D. Chlorophyll
Explanation:
Chlorophyll is important as it allows the plant to convert carbon dioxide and water into glucose.