The correct answer is - 
E. double coincidence of wants
        
             
        
        
        
A dependent variable is how they are recording, measuring or keeping track of the science experiment their doing.
A independent variable is the things/types there using to compare what is the most/least affective in the experiment.
A controlled variable is something that stays the same in the experiment or a group/set used for comparison
        
             
        
        
        
Answer:
Organisms that are more complex, such as eukaryotes, have cells that are specialized for specific functions. Gene regulation needs to be more complex to produce these specialized cells for complex organisms. Please Mark Me Brainliest
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Answer:
What animal phylum do leeches belong in?
Explanation:
Leeches are segmented parasitic or predatory worms that belong to the phylum Annelida and comprise the subclass Hirudinea. They are closely related to the oligochaetes, which include the earthworm, and like them have soft, muscular, segmented bodies that can lengthen and contract.
 
        
                    
             
        
        
        
Answer:
Due to the earth spherical shape, different latitudes of the planet receive varying solar energy levels from the sun. This is due to the differences in how the sun rays hit the earth surfaces and differences in the length of atmosphere the rays have to travel before they reach the earth's surface.
The equatorial regions get the most energy levels from the sun hence their atmosphere gets heated faster and the hottest. The air mass in this latitude, therefore, gets less fast dense  and begins to rise. The cooler and denser air mass from the poles rushes in, through the  lower atmosphere, to replace the void of the rising air.
When this air mass also gets heated, it too begins to rise. Remember the initial air mass cooled as it rose into the upper atmosphere. This now makes it denser than the air mas below it. As the hotter air mass begins to rise from below it pushes the cooler air mass above laterally. After the lateral movement, the air mass begins to sink slowly as it moves towards the poles because the incoming air mass gets denser than the local air mass.
The lateral movement of the convection current moving to the north is deflected to the north-west due to the Coriolis effect of the earth rotation while the lateral movement of the convection current moving south is deflected to the south-west. These pockets of convection currents are called Hadley cells.
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