Pretty sure the answer would be C, because you need the warm and cold air to mix.
        
             
        
        
        
84.798 is the mass number
        
             
        
        
        
False
reason - 
Gene testing is not full proof as there are  possibilities of discrepancies in it based on the testing procedures used and the condition of sample. Since we human beings have the same genomic structure there are chances that our DNA may match with other people who do not share a heredity with our family. Basically statistical probability is used to determine probability of paternity, relationship of any kind etc. among two individuals . usually A 99% or higher percentage of probability is considered conclusive. and thus it gene testing can not be considered as full proof