For the purposes of this Act, where a person:
(a) has in his or her possession; or
(b) imports into, or exports from, Australia ; or
(c) has in his or her possession with the intention of importation into, or exportation from, Australia ;
a traffickable quantity or a commercial quantity of a narcotic drug or of a psychotropic substance specified in Part 1 of Schedule 3, it is presumed that:
(d) the possession; or
(e) the importation or exportation; or
(f) the intended importation or exportation;
as the case may be, is with the intention of sale or supply, but that presumption is rebuttable.