Your answer is A. When I balance equations, I take inventory of what I have on each side and how many I have. So in the first equation you have 2 Na on both sides. You have 1 Cl on both sides. You have 2 Hydrogens on both sides. You have 1 SO4 on both sides. Therefore, both sides of the equation are equal AKA balanced.
Also, when balancing equations, it's easier to leave your sulfates, sulfites, phosphates, phosphites, etc. in their formula because it's easier to balance.
I hope I was able to help. Best of luck!
