c×v
n (NaOH) = ------
1000
0.1 × 500
n (NaOH) = ----------------
1000
n (NaOH) = 0.05 moles
Mass= Mr(NaOH) × moles
Mass= (23+16+1) × 0.05
Mass=2.15 g (2.15 grams)
Magnesium combined with sulfuric acid produces magnesium sulfate and hydrogen gas.
I had the same question, it's most likely B.