Hi there!
The correct answer is baking soda. This is how one can distinguish between either acids or bases.
Acids taste simply put, acidic. You know what I am taking about. They taste really sour. We know lemon juice tastes like this. Next, if it has the dead give-away in its name. Stomach acid, and vinegar (acetic acid).
Bases taste more bitter, and they are sometimes slippery. Baking soda on its own is very bitter.
I hope this helps now, and for any future issues you may have on this subject.
Brady