“Defense preparation” means any of the following:
(a) The manufacture, transportation, or storage of any product to be used in the preparation of the United States or any of the states for defense or for war or in the prosecution of war by the United States or in the rendering of assistance by the United States to any other nation in connection with that nation’s defense.
(b) The manufacture, transportation, distribution, or storage of gas, oil, coal, electricty, or water.
(c) The operation of any public utility.
(Added by Stats. 1953, Ch. 68.)