Correct Option: A

When sodium bicarbonate is strongly heated, it decomposes into sodium carbonate, water vapor, and carbon dioxide. Solid sodium carbonate is a white powder and is used in cooking under the name ‘baking powder’; sodium bicarbonate is used in baking under the name ‘baking soda’.
2NaHCO₃ (s) ⇒ Na₂CO₃ (s) + CO₂(g) + H₂O (g)