Correct Option (c)
All three categories listed-butterflies, fish, and frogs-include species that are either poisonous or venomous.
- Butterflies: Certain butterfly species are poisonous. They acquire toxic compounds, such as cardiac glycosides, from their host plants during larval development. These toxins are retained into adulthood, rendering the butterflies unpalatable or harmful to predators. An example is the African giant swallowtail (Papilio antimachus).
- Fish: Many fish species are venomous, possessing specialized venom glands and delivery systems, commonly in their spines. The Reef Stonefish, for instance, is highly venomous, capable of injecting potent neurotoxins through its dorsal spines. Other examples include lionfish and stingrays.
- Frogs: Numerous frog species are poisonous, secreting toxins through their skin as a defense mechanism (e.g., poison dart frogs from the family Dendrobatidae). Additionally, a few rare species, such as Bruno's casque-headed frog and Greening's frog, are venomous, delivering toxins via specialized spines.
Incorrect Options:
Options (a) Only one, (b) Only two, and (d) None are incorrect because all three groups-butterflies, fish, and frogs-have documented poisonous or venomous species among them. Therefore, these options do not accurately reflect the presence of such species across all listed categories.