Number 2 is D, and number 3 is c. But I don’t know what the answer to the number one, sorry
        
             
        
        
        
Which statement best describes the circadian rhythm? In a 24-hour period of time, we spend a period of time awake and a period of time asleep.
 
        
                    
             
        
        
        
Answer: The full form of POLICE is Public Officer for Legal Investigations and Criminal Emergencies. They are uniformed individuals who are responsible for keeping law and order intact. They are a group of personnel who are there to enforce laws, to prevent any kind of civil disorder, save lives and punish criminals.
Explanation:
 
        
             
        
        
        
Answer:
The tread on the road declined sharply till in the 13th century,when the conquests of the Mongols ushered in an era of frequent and extended contacts between East and West...
With less cost,harassment and danger,many goods and materials that the Silk Road could not transfer were conveyed through the sea route.
 
        
                    
             
        
        
        
I think he made a desicion that people can only learn from nature not harsh life