Explanation:
(1). It is known that in a reaction equation, reactants are placed or written on left hand side and products are written on the right hand side.
For example, 
Hence, in a reaction equation you start with the reactants and end up with the products.
(2). The number of atoms in a reaction will remain the same because according to the law of conservation of mass, mass of reactants will be equal to the mass of products.
Therefore, number of atoms on the reactant side will be equal to the number of atoms on product side.
ANSWER:A.blood
WHY: because it make the most sense and it seem right
Can I get brainly
Answer is: key
design change for HFC-134a A/C systems versus CFC-12 A/C systems was quick
couple service fitting and that design reduce venting and mixing of
refrigerants during service.
<span>
Level of contamination is also reduced
and the emission of refrigerants and greenhouse gases (sulfur
dioxide, carbon dioxide) is also reduced.</span>