Which of the following is a common cholinergic effect?

Cholinergic effects are outcomes that occur when acetylcholine, a neurotransmitter in the body, is activated. The activation of the cholinergic system typically leads to an increase in bodily functions related to the "rest and digest" state. Salivation is a well-known cholinergic effect, as this system stimulates the salivary glands to produce saliva, aiding in digestion. This response facilitates the breakdown of food and promotes oral health.

Other bodily responses associated with cholinergic activity include increased gastrointestinal motility, increased secretion of digestive enzymes, and enhanced secretion of mucus in the respiratory tract. Therefore, salivation is a prime example of how stimulating the cholinergic system positively impacts physiological processes, making it the correct choice in the context of this question.