A naturally occurring toxin present in certain puffer fish is:

Correct option is B

The correct answer is Tetrodotoxin, a potent neurotoxin naturally found in certain species of puffer fish ( family Tetraodontidae), as well as in some species of newts, frogs, and marine snails.
Characteristics of Tetrodotoxin:
It is extremely toxic, even in minute quantities.
It blocks sodium channels in nerve cells, preventing signal transmission and leading to paralysis and potentially respiratory failure.
There is no known antidote, and treatment is primarily supportive.
Despite its danger, puffer fish (fugu) is considered a delicacy in Japan and must be prepared by licensed chefs who are trained to remove toxic parts.
Other options:
Tetramine (a): Found in some marine snails, but not puffer fish.
Gempylotoxin (c): Associated with oilfish and escolar, not puffer fish; causes gastrointestinal symptoms.
Ciguatoxin (d): A marine toxin produced by dinoflagellates and found in reef fish like barracuda and grouper.
Thus, the correct answer is Option (b).