6.—A producer shall not be liable under this Act if he proves—

(a) that he did not put the product into circulation, or

(b) that, having regard to the circumstances, it is probable that the defect which caused the damage did not exist at the time when the product was put into circulation by him or that that defect came into being afterwards, or

(c) that the product was neither manufactured by him for sale or any form of distribution for an economic purpose nor manufactured or distributed by him in the course of his business, or

(d) that the defect concerned is due to compliance by the product with any requirement imposed by or under any enactment or any requirement of the law of the European Communities, or

(e) that the state of scientific and technical knowledge at the time when he put the product into circulation was not such as to enable the existence of the defect to be discovered, or

(f) in the case of the manufacturer of a component or the producer of a raw material, that the defect is attributable entirely to the design of the product in which the component has been fitted or the raw material has been incorporated or to the instructions given by the manufacturer of the product.