A. Notwithstanding R.S. 9:2800.56, a manufacturer of a product shall not be liable for damage proximately caused by a characteristic of the product's design if the manufacturer proves that, at the time the product left his control:
(1) He did not know and, in light of then-existing reasonably available scientific and technological knowledge, could not have known of the design characteristic that caused the damage or the danger of such characteristic; or
(2) He did not know and, in light of then-existing reasonably available scientific and technological knowledge, could not have known of the alternative design identified by the claimant under R.S. 9:2800.56(1); or
(3) The alternative design identified by the claimant under R.S. 9:2800.56(1) was not feasible, in light of then-existing reasonably available scientific and technological knowledge or then-existing economic practicality.
B. Notwithstanding R.S. 9:2800.57(A) or (B), a manufacturer of a product shall not be liable for damage proximately caused by a characteristic of the product if the manufacturer proves that, at the time the product left his control, he did not know and, in light of then-existing reasonably available scientific and technological knowledge, could not have known of the characteristic that caused the damage or the danger of such characteristic.