Answer:
The polymerase chain reaction relies upon unusual, heat-resistant __DNA polymerase molecules______ that were isolated from bacteria living in hot springs.
Explanation:
 
        
             
        
        
        
B, virtues. 
 A virtue is a trait or quality that is deemed to be morally good and is valued as a foundation of principle and good moral being. Personal virtues are characteristics valued as promoting collective and individual greatness.
        
             
        
        
        
Scientists use radio technology in order to track endangered species. These include radio collars, tags and chips. These devices can then be tracked wither via satellites through GPS technology or by locating the radio waves emitted by these devices using receivers.
These devices have proven very helpful in tracking organisms and monitoring their populations. 
        
                    
             
        
        
        
I think the correct answer from the choices listed above is the last option. Some gaming marketers focus on <span>people in their 20s </span>of the population. Because they encourage these group to chill at times or rest after all the work done in a day. Hope this answers the question.