I think it’s B. I’m not 100% sure but I believe it is B! Srry if this is late btw.
Answer:
The expression to calculate the mass of the reactant is 
Explanation:
<em>The amount of heat released is equal to the amount of heat released per gram of reactant times the mass of the reactant.</em> To keep to coherence between units we need to transform 1,080 J to kJ. We do so with proportions:

Then,

First, you need to count copper mass in alloy.
Second, you have to make an equation an find x ( the copper mass must be added). The answer is: 13,5g pure copper