The correct answer is c. smoke stacks.
Smoke stacks are chimneys or funnel shaped structures which emit smoke from a factory, vehicles and industrial set ups. Smoke stacks mostly discharge carbon dioxide and water vapor and oxides of nitrogen into the atmosphere. The exhaust released from smoke stacks cause air pollution. Air pollution can cause ailments like asthma and cancer. Thus, smoke stacks are not a source of water pollution.  
 
        
             
        
        
        
Answer:
it reacts easily with other substances. This is why they easily rust and oxidize when in contact with oxygen, and tarnish when meets water.
 
        
                    
             
        
        
        
Answer: A, B, and D
Explanation: I just took the test
 
        
             
        
        
        
It reveals that they have relationships of being friends.
        
             
        
        
        
<span>B. Knowledge and valuable resources are shared among scientists.
Being involved in a research community could provide a higher chance to researchers the privilege to avail resources, knowledge and supporting evidences that might relate or support the current study the research wants to delve into.</span>