A) lithium and beryllium 
Explanation:
From the given row on the periodic table, only lithium and beryllium will conduct electricity. 
What makes a substance able to conduct electricity? 
- The presence of free mobile electrons and in some, ions allows them to carry electric currents. 
Metals are generally known to be good conductors of heat and electricity. This is because, metals have a large pool of electrons i.e free mobile electrons. They are electropositive with a large size and readily release their electrons for conduction. 
Lithium and Beryllium are in the metallic block on the periodic table. 
Learn more: 
Metals brainly.com/question/2474874
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Circularity system........…….......
        
                    
             
        
        
        
B. Helium because it is constantly being made in the sun
Explanation:
From the given paragraph, we can conclude that helium is the most common element in a star such as the sun because it is constantly being made. 
In the nuclear fusion process that results in the production of helium, hydrogen nuclei are the reactants and helium is the product. 
- since the reactants are constantly being used in the core of the sun, this suggests that the products must be more. 
- The reaction requires a high temperature and pressure to initiate. 
- It is a series of chain reaction that uses a fuel of hydrogen to produce helium. 
learn more: 
Transmutation brainly.com/question/3433940
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Cl2 is the answer. Hope this helps you.