Final answer:
A poison is any substance that causes harm to an organism, typically through chemical reactions when ingested in sufficient quantities. Toxins are natural poisons produced by organisms, while venoms are a specific type of toxin delivered by bites or stings. The toxicity of a substance can depend on the dose-response relationship .
Therefore correct option is A
Step-by-step explanation:
A substance causing harm to an organism through ingestion can be referred to as a poison. In biology, a poison is defined as a substance that can cause death, injury, or harm to organs if a sufficient quantity is absorbed. Poisons can be found in various forms, including contaminants in the environment, natural poisons in food, and chemicals that may affect the nervous system like lead and mercury.
The term toxin is used specifically for poisons that are produced by organisms in nature, whereas venom refers to toxins that are delivered through bites or stings. Not all substances are harmful; for instance, some are essential in small amounts but can be poisonous in larger doses, illustrating the importance of a dose-response relationship in toxicology. It's also worth noting that drugs can act as poisons when consumed inappropriately.