Answer:
A. KOH + H₂SO₄ ⟶ KHSO₄ + H₂O
Step-by-step explanation:
The equation has the same number of atoms of each type on either side of reaction arrow.
B. is wrong. Atoms are balanced but the formula of sodium sulfide is incorrect.
C. is wrong. 2 Na on left and 1 Na on right.
D. is wrong. 1 N on left and 2 N on right.