According to Weber's law, the size of a just noticeable difference or difference is a constant proportion of the size of the initial stimulus.
Explanation: Weber’s law is a principle that describes that for two stimuli to be perceived as different, the stimuli should differ by a minimum constant percentage and not by a constant amount. 
For example: in a noisy room it is required to shout in order to be heard in contrast a whisper can be heard in quiet room. For us to be aware consciously 50% of the time the minimum stimulation required for any stimuli. 
The absolute threshold for difference between the two stimuli of any individual may vary and depends on the strength of the signal apart from the experience, alertness, expectation and motivation.
 The individual’s difference threshold also known as just noticeable difference is the difference between two stimuli half of the time that we can distinguish.
 
        
             
        
        
        
Friday, September 22
Autumn
Longer nights, Shorter Days.
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-Joker7721
        
                    
             
        
        
        
Answer: I think the answer is A. because I remember doing it when we were still in school I chose A. and I got a 100%.
 
        
             
        
        
        
Crossing over? That involves the random exchange of chromosomes.