The correct answer for the question that is being presented above is this one:
(1) contracting cloud of gas and dust
(2) protostar
(3) main-sequence O star
(4) red supergiant
(5) supernova
<span>(6) neutron star</span>
Here are the following items to be arranged:
<span>- protostar
- supernova
- contracting cloud of gas and dust
- main-sequence O star
- red supergiant
- neutron star</span>
        
             
        
        
        
Answer:
B
Explanation:
It is because burning fossil fuels release sulfur dioxide which causes acid rain.
 
        
                    
             
        
        
        
the nuclear stockpile of the United States peaked in 1967
 
        
                    
             
        
        
        
Answer:
All villagers were ranked by their abilities and level of skill.
Explanation:
After the hunting-gathering period, in the human history, people began to settle down. This transition of people from homes built for certain time to permanent settlements. 
This transition era is known as Neolithic Revolution. This period also marked the beginning of human civilization and social stratification. People began to cultivate lands, domesticate animals, etc. 
As the society begin to expand, social stratification became more divisive. People began to divide social class based on the resources they owned, their skills, and abilties. 
Thus the correct answer is the first option.