(b) Such property shall not be deprived of such exemption because while in the warehouse the personal property is assembled, bound, joined, processed, disassembled, divided, cut, broken in bulk, relabeled, or repackaged for delivery out of state, unless such activity results in a new or different product, article, substance or commodity, or one of different utility.
(c) Personal property of inventories of natural resources shall not be exempt from ad valorem taxation unless required by paramount federal law.
(d) The exemption allowed herein shall be phased in over a period of five consecutive assessment years, at the rate of one fifth of the assessed value of the property per assessment year, beginning the first day of July, one thousand nine hundred eighty-seven.