Answer:
I believe it is C. Crawfish prefer the food source at location 4.
Explanation:
 
        
             
        
        
        
Answer:
Oxygen
Explanation:
A waste product of photosynthesis organisms need for cellular respiration is oxygen. We breathe out carbon dioxide and plants use carbon dioxide during photosynthesis and in return they give us oxygen which is their waste product. 
 
        
             
        
        
        
The bias conditions that must be present for the normal operation of a
transistor amplifier will be those in which the emitter-base junction is
forward biased, and the collector-base junction will be reverse biased.
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