The compound present in baking soda is:

Baking powder is a white substance that is added to bread and cakes to make them soft and fluffy.

Baking powder is basically a mixture of sodium bicarbonate and an acidic component usually tartaric acid. When water is added to the baking powder, it releases carbon dioxide gas that raises the volume of the baked goods. As a source of carbon dioxide and an ingredient in baking powders, effervescent salts, beverages, and dry chemical fire extinguishers, sodium bicarbonate (${\mathrm{NaHCO}}_3$), often known as baking soda, bicarbonate of soda, or sodium hydrogen carbonate, is a white crystalline or powdered solid.

Thus, the compound present in baking powder is sodium bicarbonate (${\mathrm{NaHCO}}_3$).

Hence, option A is correct.