Final answer:
Effervescent salts are the drugs that bubble when dissolved in water due to the reaction between an acid and a base in the salts, producing carbon dioxide gas.
Step-by-step explanation:
Out of the options given, the drug that bubbles is effervescent salts. Effervescent salts are compounds that release gas when dissolved in water, producing a bubbling or fizzing effect. This is due to the reaction between an acid and a base present in the salts, which generates carbon dioxide gas.