Answer:
The right answer to this question is the second option: Exothermic reaction
Explanation:
This can be said because, by knowing that an exothermic reaction will always release energy from the reaction, and that's what is happening here, when you dissolve the antacids in water the temperature starts dropping, and that means that the water is losing energy to the environment because of the reaction.
An endothermic reaction would cause this reaction to absorb energy from the environment, but that's not what happened.
