The correct answer is Sour candies.

A sialagogue is any substance that stimulates the production and secretion of saliva. Among the options provided:

- Pilocarpine is a cholinergic agonist that stimulates muscarinic receptors to increase saliva production and is often used medically to treat dry mouth. However, it is a prescription medication rather than a commonly used sialagogue in daily practice.

- Sour candies are commonly used as a simple, over-the-counter means to stimulate saliva production. The acidic taste of sour candies activates taste receptors, which reflexively stimulate the salivary glands to produce more saliva. This effect is immediate and widely used to relieve dry mouth symptoms.

- Atropine and anticholinergic drugs have the opposite effect; they inhibit muscarinic receptors and therefore reduce saliva production, often causing dry mouth as a side effect.

In summary, while medications like pilocarpine can stimulate saliva, in common and practical use, sour candies are the frequently employed sialagogues due to their easy availability and direct stimulation via taste sensation.

Reference: Pharmacology, 7th Edition, Katzung/Berenbaum, Chapter 17: Drugs Affecting the Autonomic Nervous System, Page 320