D. Baking soda produces bubbles when vinegar is poured on it.
Explanation:
Acetic acid = C₂H₄O₂
Baking soda = NaHCO₃
C₂H₄O₂ + NaHCO₃ → NaC₂H₃O₂ + H₂O + CO₂
When baking soda is added to vinegar, a chemical reaction will take place producing a huge amount of carbon-dioxide in the form of bubbles in the foaming mixture.
No. You cannot rule out the battery even after the open circuit voltage measurement. The open-circuit voltage may not have changed but the battery's internal resistance may have greatly increased.