Answer: The correct answer is C) Citric acid.
As per the property of acid and base, acids are sour in taste and bases are bitter in taste. Citric acid is a weak organic acid that is naturally found in citrus fruits (like orange). It is used as ingredient to make super sour candies.
On the contrary, Nitric acid is a highly corrosive mineral acid so it can not be used as ingredient in candies. Zinc hydroxide and calcium hydroxide are bases.
Thus, C) is the right answer.