In a proceeding for an offence against this Act, it is presumed until the contrary is proved, on the balance of probabilities, that—
(a) a substance that is part of a batch, lot or consignment of the substance of the same kind or description is representative of all of the substance in the batch, lot or consignment; and
(b) each part of a sample of a substance divided for analysis for this Act is of uniform composition with every other part of the sample; and
(c) a person who sold a substance in the conduct of a business and was not the holder of a licence sold the substance as the employee of the licensee; and
(d) a person who appears from any marking or label on an article, container or package containing a substance for sale to have manufactured, imported, packed or supplied the substance is a person in control of the manufacture, import, packing or supply of the substance.