Which of the following best defines a poison?

A poison is best defined as a substance that causes harm when ingested or produced in the body. This definition encompasses various substances that can disrupt normal biological functioning, leading to adverse effects or even death, depending on the dose and the individual's susceptibility. Poisons can be naturally occurring or man-made and may vary in severity from mild to life-threatening.

While nutrients are essential for life and medicinal compounds can be beneficial when used appropriately, they do not fit the definition of a poison. Similarly, a benign plant extract does not have harmful effects on the body and would not be classified as a poison. This understanding is crucial in fields such as toxicology, pharmacology, and medicine, where the effects of various substances on the body are critically examined.