Which of the following is a symptom of alkaloid poisoning?

Pupil dilation is a well-known symptom associated with alkaloid poisoning, particularly due to substances such as atropine, which is derived from plants like belladonna. Alkaloids can mimic certain neurotransmitters in the body, leading to various physiological effects. When the body is exposed to alkaloids, their influence on the autonomic nervous system can result in dilation of the pupils, also known as mydriasis. This occurs as alkaloids can block the action of acetylcholine on the parasympathetic nervous system, which normally constricts the pupils.

Understanding the role of alkaloids and their interaction with neurotransmitter systems is crucial in identifying signs of poisoning. The other options listed, such as increased appetite, skin rashes, and muscle cramps, are not commonly associated with alkaloid toxicity in the same way as pupil dilation is. Instead, they may be indicative of other types of poisoning or health conditions, making pupil dilation a more definitive and recognized symptom of alkaloid poisoning.