Answer:- NaBr and Cl2 are reactants .
The atoms/molecules/ions on RHS of the reaction which react to give products are called reactants.
So here Sodium bromide and chlorine are the reactants.
Option A is the correct choice.
Additional information:-
Law of conservation of Mass :-
According to this law , the mass of reactants is equal to the mass of the products . Take a chemical reaction ,
C + O2 ==> CO2
Now suppose that if 12g of carbon reacts with 16g of oxygen to form carbon dioxide, then what will be the mass of carbon dioxide? So by law of conservation of Mass we can say that mass of carbon dioxide will be equal to mass of the reactants that will be 12g + 16g = 28g
With this I am leaving a sample problem for you to solve,
Question: Consider the following reaction .
2C + O2 ==> 2CO
If the mass of carbon taken is 24g and the amount of carbon monoxide formed is 56g , find the amount of oxygen used in the reaction.