Which of the following scenarios best demonstrates a physiological adaptation rather than a structural or behavioural adaptation in an Australian organism?
- A kangaroo's ability to hop at high speeds over long distances.
- The drought deciduousness of mulga trees in arid regions.
- The mallee fowl's behaviour of building and maintaining large incubation mounds.
- The production of cyanide compounds by Swainsona plants when grazed upon.