We de-starch leaves so as to remove the starch produced in it during photosynthesis stored as food. Removing the starch would help us to infer our observations clearly as there is no change or substance that would effect the experiment we want to carry out. For example , the indicators we use might give blue-black or green colors just because of the presence or absence of starch.
        
             
        
        
        
Answer: feed-back 
When the product of a metabolic pathway accumulates, it may be able to slow down or turn off the pathway by inhibiting the activity of an enzyme that catalyzes an early step in the pathway. This is referred to as feed-back inhibition.
Explanation:
Feed-back inhibition is said to occur when the final product of a biochemical pathway signal the inactivation of the starting materials of the pathway. 
For example: when pyruvate signal the inactivation of phosphofructokinase, the glycolytic pathway gets turned off. 
 
        
             
        
        
        
Arthropods has the bilateral symmetry !
so answer is B !