Which of the following is NOT an example of a choline ester?

The question asks for an example of a compound that does not belong to the category of choline esters. A choline ester is defined as a compound that contains choline (or a choline derivative) and typically acts as a cholinergic agent. Acetylcholine (ACh), cevimeline, and carbachol are all classified as choline esters because they are structurally derived from choline and mimic the action of acetylcholine at cholinergic receptors.

On the other hand, atropine is not a choline ester. It is a tertiary amine that is derived from tropine and is known for its anticholinergic properties. Atropine blocks the action of acetylcholine at muscarinic receptors, leading to effects such as increased heart rate and decreased secretions. This distinction places atropine outside the category of choline esters, clearly making it the correct answer as it does not share the structural characteristics or pharmacological profile of the other options.