Concept:Defensive adaptations are body structures or behaviours that protect an animal from being eaten by predators.
Explanation:The porcupine fish has sharp spines covering its body.
When threatened, it quickly sucks in water and swells up like a ball.
This makes the spines stand out rigidly in all directions.
A predator that tries to swallow it now faces a painful, prickly mouthful.
The inflated fish becomes very difficult to bite, grip, or swallow.
This mechanism is a clear physical defense against enemies.
The option "spines in porcupine fish" directly matches this adaptive defense strategy.
Croaking in a male toad is mainly for attracting a mate, not defense.
Basking in a lizard is for regulating body temperature, not defense.
Huddling in penguins is for conserving heat in cold conditions, not defense.
Answer:C. spines in porcupine fish