Answer:
The answer is A) relative motion.
Explanation:
As the name suggests, relative motion refers to the perceived velocity of a point in relation to another. 
Some more instances would be the perceived velocity of a car if you're standing the next to the road (the car moves fast), if you're driving a car and moving at the same speed (the other car appears static) or if you're driving the opposite direction (the other car appars to move at double the speed). 
It's important to notice that relative motion can be positve or negative. 
 
        
             
        
        
        
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During the Russian Revolution, the Bolsheviks, led by leftist revolutionary Vladimir Lenin, seized power and destroyed the tradition of csarist rule. The Bolsheviks would later become the Communist Party of the Soviet Union.Feb 28, 2020
        
             
        
        
        
Two types of sexual dysfunction
 
        
             
        
        
        
Answer:B) Culture
Explanation: Culture simply means the way of life of a particular society, this way of life includes their beliefs, norms and values, arts, custom, language etc.
Davi and Nirant staying in America to gain an understanding of how Americans live their lives simply means they are trying to understand the culture of Americans.
Understanding the culture of other people in a different societal settings other than yours help one understand why people do what they do in their society.