Answer:B. 
It was used to prove that smoking causes health problems.
Explanation:
 
        
                    
             
        
        
        
The cost of the electricity if 42000 kWh of electricity is used is ;  $1680
<h3>Determine the cost of electricity </h3>
<u>Given that ;</u>
value of electricity used = 42000 kWh 
cost rate of electricity = $0.04/kWh 
 
Final step : Determine the total cost of electricty used 
unit cost = $0.04/kWh 
Totals cost = unit cost * value of electricity used 
                   = 0.04 * 42000 = $1680
Hence we can conclude that The cost of the electricity if 42000 kWh of electricity is used is ;  $1680. 
Learn more  about Electricity cost : brainly.com/question/14277272
 
        
             
        
        
        
Nucleotides are being named or classified by their bases. They are adenine, cytosine, guanine, thymine and uracil. Nucleotides are organic molecules that serve as the monomers, or subunits, of nucleic acids like DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).
        
             
        
        
        
Answer:
1st point describes both the sperm and ovum.